(covers information from several alternate timelines)
The Borg were a pseudo-species of cybernetic humanoids, or cyborgs, from the Delta Quadrant known as drones. No single individual truly existed within the Borg Collective (with the possible exception of the Borg Queen), as all Borg were linked into a hive mind which connected all of them and allowed information from every drone who had been brought into the collective to be shared. Their ultimate goal was the attainment of 'perfection' through the forcible assimilation of diverse sentient species, technologies, and knowledge which would be added and absorbed into the hive mind. As a result, the Borg were among the most powerful and feared entities in the galaxy, without really being a true species at all.
The physiology of each Borg drone varied according to the species from which it was assimilated. (Star Trek: First Contact) Drones were typically humanoid, although the Collective demonstrated a willingness to assimilate non-humanoid lifeforms. (VOY: "Scorpion")
Upon assimilation, a drone ceased to grow body hair and developed an ashen, grayish skin coloration, ignoring original skin pigmentation. Cybernetic implants were either surgically attached to the body or grown internally by nanoprobes injected into the bloodstream; in certain cases these implants could cause severe skin irritation. (TNG: "The Best of Both Worlds"; Star Trek: First Contact) The nature of these implants varied from drone to drone depending on the drone's intended function, but basic nodes of interlink for communications with the Collective and a myo-neural cortical array to control movements were implemented in every drone. In most cases, an eye would be replaced with an eyepiece that improved vision and an arm would be amputated altogether to make room for a functional prosthetic; in tactical drones, a weapon would be included, and some drones had medical tools built in to heal drones who had minor injuries. (VOY: "The Gift", "Dark Frontier") The implants of a fully assimilated drone allowed it to function for extended periods without shelter, food, water, or even air. It could even survive in the vacuum of space. Lily Sloane, a human observer local to Earth of the 21st century, characterized Borg drones as "bionic zombies" after hearing a description of them, albeit before observing them directly. (Star Trek: First Contact)
A drone's only requirement was a supply of energy to maintain the implants that in turn maintained its biological functions. This energy was supplied during regeneration cycles within a Borg alcove. Upon receiving damage, a drone would return to the alcove for assessment of the damage. Severely damaged drones were disassembled and scavenged for reusable parts. (TNG: "Q Who", "I Borg")
The Borg did not procreate; they added to the Collective's population only by assimilation. (VOY: "Drone") Borg infants were not accepted to the collective until they matured to a certain age. Until reaching this age, assimilated infants and youths were placed inside maturation chambers. (TNG: "Q Who"; VOY: "Collective")
Borg drones were equipped with myriad technologies integrated into their bodies which enabled them to perform their duties within the Collective, several of which were universal to all drones. A neural transceiver kept them connected to the hive mind. (VOY: "Scorpion, Part II") A personal force field protected each drone from most energy-based attacks. (TNG: "Q Who") A drone was able to communicate with their ship with signals across a subspace domain, the basis of their hive mind, which Data likened to a transporter beam. (TNG: "The Best of Both Worlds, Part II") Each drone possessed a pair of assimilation tubules embedded in one hand for the purpose of instantly injecting individuals with Borg nanoprobes. (Star Trek: First Contact) A cortical processor allowed a drone to rapidly assimilate visual information. Borg drones were also equipped with a neural processor, which kept a record of every instruction that particular Borg receives from the collective hive mind. Captain Picard used one such processor to discover that the Borg were attempting to use the deflector dish of the USS Enterprise as an interplexing beacon to contact the Borg in 2063. (Star Trek: First Contact)
Drones also contained fail-safes designed to deactivate and even vaporize their own bodies, thereby allowing the Collective to eliminate damaged or dead drones without leaving remains to be exploited by outsiders. (TNG: "Q Who") The captured drone Third of Five also made comments indicating that this vaporization may have been a form of resource re-absorption. (TNG: "I Borg") One of these fail-safes was intended to automatically deactivate drones experiencing strong emotional states, which the Borg interpreted as a sign of disconnection from the hive mind. (VOY: "Human Error")
The Borg typically operated in an atmosphere with a constant temperature of 39.1 °C (102.38 °F), 92% relative humidity, an atmospheric pressure of approximately 102 kPa, and trace amounts of tetryon particles. (Star Trek: First Contact)
- Main article: Borg history
The precise origins of the Borg were unclear. As of 1484, they were reported as controlling only a handful of systems in the Delta Quadrant, but by 2373, they had assimilated thousands of worlds. In addition to this stronghold in the Delta Quadrant, the Borg also dispatched vessels throughout the galaxy via transwarp conduits. (VOY: "Dragon's Teeth", "Scorpion", "Endgame")
A Borg vessel traveled back in time from 2373 in an unsuccessful attack on Earth in 2063. (Star Trek: First Contact) Drones which survived this defeat were discovered and reactivated by Human scientists in 2153, and transmitted a subspace message to Borg space before being destroyed by Enterprise NX-01. (ENT: "Regeneration")
The Borg entered the home system of the El-Aurians at some point in their mutual history, swarming through it, scattering its native inhabitants and leaving little to nothing of the El-Aurians in their wake. (TNG: "Q Who", "I Borg") In 2293, the Federation offered aid to El-Aurian refugees fleeing the Borg. (Star Trek Generations) These refugees included Guinan, who would later provide secondhand knowledge of the Borg invasion of the El-Aurian system to the crew of the USS Enterprise-D during an encounter in the 24th century. (TNG: "Q Who", Star Trek Generations) However, each of these earlier incidents contributed almost nothing to the Alpha Quadrant's awareness or understanding of the Borg Collective.
By the 2350s, rumors of an alien race called "The Borg" had reached the Alpha Quadrant, inspiring exobiologists Magnus and Erin Hansen to set out in search of them. Their research took them all the way to the Delta Quadrant before they and their daughter Annika were assimilated in 2356. (VOY: "The Gift", "The Raven", "Dark Frontier") Borg activity in the Alpha Quadrant, including the assimilation of the USS Tombaugh in 2362 and assimilation of outposts along the Romulan Neutral Zone in 2364, were complete mysteries to Starfleet. (VOY: "Infinite Regress"; TNG: "The Neutral Zone")
In late 2366, a Borg cube invaded Federation space and assimilated Jean-Luc Picard, whose tactical information contributed, along with the Borg's own vastly superior power, to Starfleet's disastrously one-sided engagement with the cube, the Battle of Wolf 359. A fleet of forty starships assembled to combat the cube. All but one of these ships were destroyed, while the cube remained intact, damaged but healing rapidly. (TNG: "The Best of Both Worlds", "The Best of Both Worlds, Part II"; DS9: "Emissary") The Enterprise-D recovered Picard and used his connection to the hive-mind to disable the cube before it could attack Earth. (TNG: "The Best of Both Worlds, Part II")
The Borg-Species 8472 War decimated the Collective from 2373-2374. (VOY: "Scorpion", "Scorpion, Part II") Voyager's liberation of Seven of Nine allowed Unimatrix Zero to create an active resistance movement in 2377. (VOY: "Unimatrix Zero", "Unimatrix Zero, Part II")
In 2378, a crippling blow was delivered to the Borg when Voyager discovered one of their transwarp hubs and destroyed it, killing the Borg Queen (again) and devastating the Unicomplex in the process. During this battle, the Borg were infected with a neurolytic pathogen, which was carried by an alternate future version of Admiral Janeway and designed to disrupt the hive mind, to 'bring chaos to order'. It was this pathogen that killed the Borg Queen, and allowed Voyager to destroy the transwarp hub. (VOY: "Endgame")
In one alternate quantum reality, Captain Jean-Luc Picard was lost in the Battle of Wolf 359 and William T. Riker succeeded him as the captain of the Enterprise-D with Worf as his first officer. (TNG: "Parallels")
Victory at Wolf 359
In another alternate quantum reality, the Borg emerged victorious from Wolf 359 and successfully conquered the Federation. A battered Enterprise-D which was likewise under Riker's command was one of the few remaining Starfleet ships by 2370. That reality's Riker was desperate not to return to his universe once all of the Enterprises began spilling into a single universe from a quantum fissure.
After the present reality's Enterprise-D fired lightly upon the other ship to draw the alternate reality crew's attention away from that crew's attempt to prevent the closing of the fissure, the heavily damaged ship was accidentally destroyed when its shields collapsed and their warp core overloaded, due to having a weakened warp containment field, as Riker presumed, from fighting with the Borg. (TNG: "Parallels")
In another alternate timeline, the Borg were successful at preventing First Contact in 2063 and assimilated the Earth. In 2373, the assimilated Earth had an atmosphere containing high concentrations of methane, carbon monoxide, and fluorine. It had a population of approximately nine billion Borg drones. (Star Trek: First Contact)
- See also: Borg philosophy
The Borg Collective was made up of at the very least trillions of humanoids referred to as drones. (VOY: "Dark Frontier") Through the use of their cybernetic implants, the Borg interacted by sharing one another's thoughts in a hive mind. Upon assimilation, these trillions of "voices" would overwhelm the drone, stifling individual thought and resistance to the Collective's will. (TNG: "Family") To some drones these voices could eventually become a source of comfort, and their absence a source of pain. (TNG: "I Borg"; VOY: "The Gift")
Borg philosophy was governed by a primary directive to add the biological and technological distinctiveness of other species to that of the Borg. In this manner, the Collective sought to achieve its definition of perfection; all other pursuits were deemed irrelevant. Accordingly, Borg drones did not engage in any activities except their duties and regeneration. (TNG: "Q Who", "The Best of Both Worlds"; VOY: "Scorpion, Part II") Individual drones have demonstrated puzzlement at other species' unwillingness to be assimilated, the drones believing in the superiority of their way of life.
Having no regard for individuality, Borg drones were identified with designations rather than names. A drone's designation typically described its position within a group, e.g. "Third of Five." To more specifically identify a drone, its function could be appended to this designation, for example "Seven of Nine, Tertiary Adjunct of Unimatrix 01." In the same manner, the Borg refer to alien species by number rather than by name. (TNG: "I Borg"; VOY: "Scorpion")
If a drone was sufficiently injured or otherwise in distress, other drones would offer assistance. (TNG: "I Borg"; VOY: "Dark Frontier") However, if a drone was deemed irreparable by the hive-mind, the Borg would deactivate it and redistribute any salvageable components throughout the Collective. (TNG: "Q Who")
Borg drones ignored alien species until they demonstrated the potential to be a threat or a suitable candidate for assimilation. This extended even to taking no notice of people boarding their vessels; the drones went about their business as long as the intruders did not interfere. When addressing a small number of individuals, drones would simply attempt to assimilate them without comment. Before assimilating a larger population, such as a starship or an entire culture, the Borg would collectively transmit a standard announcement of their purpose and the futility of resistance. (TNG: "Q Who"; VOY: "Dark Frontier"; Star Trek: First Contact) Species the Borg found unremarkable would be deemed unworthy of assimilation. As of 2374, the Borg considered the Kazon beneath their notice, and by 2376, they only took interest in the Brunali if they detected sufficiently relevant technology. (VOY: "Mortal Coil", "Child's Play")
Even examples of civilizations previously targeted for assimilation could be passed over; while moving to engage the dire threat to the Borg presented by Species 8472, a group of Borg ships encountered Voyager, but, while one ship did pause momentarily to scan the Federation vessel, the Borg ship and its companion ships quickly moved on without attempting to attack or assimilate the interloper in their space. (VOY: "Scorpion")
On the rare occasions that the Borg were willing to open a dialogue with individuals, they chose a single drone to speak for the Collective. Jean-Luc Picard was assimilated and given the name Locutus in the misguided assumption that such a representative would lower the Federation's resistance to assimilation. (TNG: "The Best of Both Worlds")
When Kathryn Janeway successfully negotiated a truce with the Borg and refused to discuss the terms via a neuro-transceiver, the Collective agreed to communicate via Seven of Nine. (VOY: "Scorpion, Part II")
The Borg Queen also spoke for the Collective, acting not as a mere liaison but as a physical manifestation of the hive mind. The exact nature of her role is unclear. (Star Trek: First Contact)
The Borg possessed a near-reverence for particle 010, which they considered to be an expression of perfection. The Collective's fascination with assimilating this molecule has been compared to a religion. (VOY: "The Omega Directive")
The Borg had a tendency to "scoop" all machine elements from a planet, leaving great rips in the surface where remaining sections of the road system suggested a city once was. (TNG: "The Neutral Zone", "Q Who"; VOY: "Child's Play")
The Borg were known to retrieve their damaged technology, including nonfunctional Borg cubes. However, when a cube underwent submatrix collapse, the collective would immediately sever its link to the afflicted population, considering it dead. (VOY: "Unity"; PIC: "Maps and Legends")
- Main article: Borg technology
Borg technology was a combination of technologies assimilated from other cultures and technology developed within the Collective in order to overcome obstacles to its goals. When confronted by a problem it could not solve with its existing resources and/or configuration, the entire Collective would work in concert to consider all possible solutions and implement the one determined to be the most efficient. By applying the unique skills of each drone to a task, the hive mind could engineer new technologies and solutions at a pace that would astound an individual. (TNG: "Q Who", "The Best of Both Worlds, Part II")
The Borg were usually exceedingly quick to adapt; their shields would often nullify nearly any energy weapon, and their weapons would usually penetrate nearly any shield or defense, within minutes. (Star Trek: First Contact)
Borg vessels were highly decentralized, with no distinct bridge, living quarters, or engineering section. Each ship was collectively operated by its complement of drones, under the general direction of the hive mind. Owing to the Collective's disregard for aesthetic considerations, the architecture of Borg ships took the form of basic shapes such as cubes and spheres and they were made from tritanium alloy. Borg ships were capable of regenerating from damage. (TNG: "Q Who"; VOY: "Endgame")
Each Borg spacecraft was equipped with a vinculum to interconnect its crew, which was in turn connected to a central plexus that linked the ship to the Collective. (VOY: "Infinite Regress", "Unimatrix Zero") In addition to warp drive, vessels were fitted with transwarp coils that could achieve even greater speed by opening transwarp conduits. (TNG: "Descent"; VOY: "Dark Frontier") When critically damaged or otherwise compromised, a Borg ship would self-destruct to prevent outsiders from studying Borg technology. (TNG: "The Best of Both Worlds, Part II") In other situations, only the valuable technology would self-destruct, such as the case of the crew of Voyager's first attempt to steal a transwarp coil. USS Voyager encountered several damaged Borg vessels, notably including the cube carrying Icheb, Mezoti, Azan, and Rebi, and a sphere carrying a transwarp coil, which Voyager stole. (VOY: "Collective", "Dark Frontier")
- See also: Borg starship classes
Borg structures were located in deep space, in planetary systems, or on planets themselves. Each planet the Borg modified showed a typical climate and assimilated infrastructure adapted from the previous inhabitants. (Star Trek: First Contact; VOY: "Dark Frontier", "Dragon's Teeth")
Buildings were simple shapes, similar to the geometrical ships, and rather than being single structures they were annexed together and added to when needed. By joining new structures to existing ones, they would form a uniformed complex. These buildings were gargantuan in size, with structures that could house Borg spheres docked inside. (VOY: "Dark Frontier")
The Borg also constructed structures that had special functions, like the transwarp hub. There were six known hub locations in the galaxy that allowed Borg vessels to deploy rapidly to almost everywhere in the galaxy. These transwarp hubs had many portal opening structures on them, and inside their corridors were interspatial manifolds which supported the transwarp conduits. Several of these manifolds that led to the Alpha quadrant were destroyed by Voyager via transphasic torpedos and collapse of the conduit itself on the vessel's return to the Alpha Quadrant. (VOY: "Endgame")
- Borg Collective
- Borg language
- Borg philosophy
- Borg spatial designations
- Borg species
- Borg species designations
- Borg starships
- DS9: "Emissary"
- Star Trek: First Contact
- "Blood Fever" (corpse)
- "Scorpion, Part II"
- "The Raven" (hallucinations)
- "The Killing Game" (database image)
- "Living Witness" (holograms)
- "One" (hallucinations)
- "Hope and Fear"
- "Infinite Regress"
- "Dark Frontier"
- "Survival Instinct"
- "Tinker Tenor Doctor Spy" (holograms)
- "Child's Play"
- "Unimatrix Zero"
- "Unimatrix Zero, Part II"
- "Flesh and Blood" (hologram)
- ENT: "Regeneration"
In addition to their appearance listed above, the Borg are also mentioned in the Star Trek: The Next Generation episodes "Family" and "Parallels", in the TNG films Star Trek Generations, Star Trek: Insurrection and Star Trek Nemesis, in the Star Trek: Deep Space Nine episodes "The Storyteller", "Playing God", "The Search, Part I", "The Way of the Warrior", "For the Cause", "Let He Who Is Without Sin...", and "In Purgatory's Shadow", as well as in the Star Trek: Voyager episode "Death Wish" and in the Star Trek: Lower Decks episode "Much Ado About Boimler".
The conceptual genesis of the Borg, intended to replace the Ferengi as Star Trek: The Next Generation's main villains in its second season, was as a race of insectoids, a concept that would ultimately require modification due to budgetary constraints. As Maurice Hurley explained in the March 1990 issue of Starlog (#152, p. 33): "What we really wanted to do, but couldn't because of money, was create a race of insects...insect mentality is great because it is relentless. The Borg are a variation of an insect mentality. They don't care. They have no mercy, no feelings toward you. They have their own imperative, their own agenda and that's it. If all of them die getting there, they don't care. We needed a villain who could make you dance, and the Borg could do it!"
Hurley made it a plot point in "The Neutral Zone" that Federation and Romulan starbases along the Romulan Neutral Zone had been mysteriously wiped out, having been "scooped off" the face of the planet in the same way that would later be referenced in "Q Who" and shown in "The Best of Both Worlds". Intentions to lay more extensive groundwork for the Borg's introduction were frustrated by the Writer's Guild strike of 1988. By the time of their first appearance in "Q Who", the species had been changed from insects to their more budget-friendly cyborg form. (Captains' Logs: The Unauthorized Complete Trek Voyages, pp. 169 & 180)
The Star Trek Encyclopedia (3rd ed., p. 52) stated: "Writer Maurice Hurley derived the name Borg from the term cyborg (cybernetic organism), although it seems unlikely that a people living on the other side of the galaxy would know of the term."
According to Michael and Denise Okuda in their Star Trek Chronology (2nd ed., p. 290), there had been plans to connect the parasitic beings from "Conspiracy" to the Borg, but these were ultimately abandoned: "At the time the episode was written, this was apparently intended to lead to the introduction of the Borg in Star Trek: The Next Generation's second season. The Borg connection was dropped before 'Q Who?' (TNG) was written, and the truth about the parasites remains a mystery." They also noted that, following production of the latter episode, it was "half jokingly speculated" by Gene Roddenberry that the machine planet encountered by Voyager 6, leading to its transformation into V'ger, "might have been the Borg homeworld." (Star Trek Chronology (2nd ed., p. 23))
The idea for the sound of the Borg's multiple voices speaking in unison was thought up by sound editor Bill Wistrom and co-producer Merri Howard. After experimenting with different techniques, they discovered a way to lay multiple voices over one another and "make it sound like it was 8 million people," explained Wistrom. (Star Trek: Communicator issue 147, p. 32)
Chronologically, the first known in-universe appearance of the Borg to Humanity was in the 1996 motion picture Star Trek: First Contact, in which the Borg traveled back to the year 2063 to enslave the Human race. The writers of the Star Trek: Enterprise episode "Regeneration", Mike Sussman and Phyllis Strong, stated, in the audio commentary on the ENT Season 2 DVD release, that it was their explicit intent to have the episode deal with the consequences of events depicted in Star Trek: First Contact, the Borg wreckage encountered in that episode being the debris of the Borg sphere destroyed by the USS Enterprise-E in that movie.
While it is not explicitly stated in "Q Who", Q implies that the sole interest of the Borg is in the technology of the USS Enterprise-D, and the Borg show no interest, in that episode, in the crew (although the segment of hull the Borg remove from the ship apparently contained several crew members). In their next appearance, "The Best of Both Worlds", the Borg's objectives had changed to assimilation of lifeforms, and this change of premise was referenced in dialogue. Subsequent episodes ignored the change in premise entirely.
Director Cliff Bole, who directed the "Best of Both Worlds" two-parter, thought highly of the Borg. He enthused, "The Borg are like Klingons. You can do anything you want with them. They're fun and a real expensive thing to play with. With them, you can do a big production value [...] The Borg allow you to have fun with the camera, the lighting and everything else. They challenge the imagination." ("Cliff Bole – Of Redemption & Unification", The Official Star Trek: The Next Generation Magazine issue 17, p. 31)
Through the course of Star Trek history, further retroactive continuity changes appear to have been made in respect of the Borg. As of "Q Who" and "The Best of Both Worlds", it appeared that Starfleet had never heard of the Borg. Subsequently, Star Trek: Voyagers "Dark Frontier" and Star Trek: Enterprises "Regeneration" showed that not only was Starfleet previously aware of the existence of the Borg, Federation scientists actually pursued them – even if they were considered mere rumor. Further, although Guinan indicates in "Q Who" that her people were attacked by the Borg, it is implied that Starfleet was not aware of the threat. However, it was later revealed in Star Trek Generations that Starfleet, in fact, rescued the El-Aurian survivors of the Borg attack including Guinan, and it seems unlikely that Starfleet would not inquire as to the cause of their plight.
The Borg were considered as an enemy for the Deep Space 9 crew (along with the Klingons, Cardassians, and the Romulans) when Star Trek: Deep Space Nine was in development. Rick Berman later commented, "The Borg are not the kind of bad guys that are practical to use on a regular basis." Whereas the Cardassians were eventually chosen for the main villain role, the Borg made no further appearances in Deep Space Nine after "Emissary", although they were mentioned in episodes such as "The Storyteller", "Playing God", "The Search, Part I", "The Way of the Warrior", "For the Cause", "Let He Who Is Without Sin...", and "In Purgatory's Shadow". (Star Trek - Where No One Has Gone Before) According to Robert Hewitt Wolfe in a tweet dated 28 January 2019, following the premiere of Star Trek: Voyager, a mandate was passed to the writing staffs of both Deep Space Nine and Voyager that the Borg (along with Q, following his single appearance on Deep Space Nine) were only to be used on Voyager while Deep Space Nine retained creative control over the Alpha, Beta, and Gamma Quadrants, which Wolfe called "a fair trade." 
The Borg were considered by some to be the greatest villains of Star Trek: The Next Generation. However, they were featured in only six episodes throughout its seven-year run. The creators have stated that this was due to the fact that the Borg were so powerful, it was not easy to come up with solutions for beating them. However, as time passed and future series went into production, the concept of the Borg evolved to include inherent flaws that could be exploited in many different ways – leading them to appearing in nineteen episodes of Star Trek: Voyager (although in only a fraction of these appearances were the Borg the primary villains; many episodes had them in supporting or otherwise non-antagonistic roles). This generous use caused many fans to complain that the Borg were being used too often on Voyager. TNG, DS9, and one-time VOY writer Ronald D. Moore once said of their perceived overuse, the Borg had been defeated so many times, that they had "lost their teeth." (citation needed • edit)
The existence of the Borg Queen was a controversial change made to the Borg during the writing of Star Trek: First Contact. While the writers had intended to stay true to the original concept of the Borg as a collective hive, they found it difficult to maintain the dramatic impact of villains without a central face. Thus, they created the Queen. In the film, she claimed to have been present during the events of "The Best of Both Worlds", which in retrospect would appear to have negated the reason for Picard's assimilation in that episode (it was claimed that the Borg needed a single representative to speak for them). While the Queen appeared to be killed at the climax of First Contact, she apparently survived unaffected by the Borg's next appearance in Voyager's "Scorpion". While many fans have attempted to reconcile this, there has never been an official explanation for her survival (save for an enigmatic comment by the Queen), and the appearance of relatively identical Borg Queens in later episodes. Some, though, have theorized that the Borg Collective contained many queens that served as focal points to different branches of their society. Still another explanation is that the Borg were in possession of innumerable copies of the Borg Queen and that the superficial death of one version simply resulted in the activation of a similar version to take her place, in a similar fashion to the Vorta. The latter theory was corroborated by Rick Berman in an interview in Star Trek: Communicator. (Star Trek: Communicator issue 121)
In an interview with StarTrek.com published on 1 April 2019, actor Alan van Sprang, who played Leland in Star Trek: Discovery, echoed fan speculation regarding a potential connection between Control and the origins of the Borg: "I think it's very intriguing. When I first read the script I thought, 'Oh, is this the making of the Borg? Is that how it happens?' We're as much in the dark as anybody else, but as soon as I saw that, I thought, 'This is like The Borg.' The Next Generation's Borg episode just blew my mind [when I watched it originally], let alone when Picard became Locutus. That's the first thing I thought of, which kind of tickled me to no end. 'Wow, I'm just going to milk this for all it’s worth.'" 
In an interview with TrekCore.com published on 19 April 2019, Michelle Paradise, then writer and co-executive producer of Discovery, clarified: "It's interesting — we weren't thinking Borg at all. I mean, we talked about all sorts of different things in the room, but there was never any intent on our part to parallel that in any way. I can certainly understand why people started to think we were going in that direction, but it was never where we intended to go with it." 
The absence of the Borg from Deep Space Nine was explained in the novel The Siege, when a Borg cube tries to pass through the Bajoran wormhole and is destroyed by subspace compression; Sisko concludes that this event will cause the entire Collective to believe that the wormhole is unstable and would now avoid it.
In the alternate timeline seen in the Star Trek: Deep Space Nine book series Millennium, the Borg forged an alliance with the Federation to defeat Weyoun. The entire Borg Collective was destroyed along with the universe. This entire timeline was later reset thanks to Benjamin Sisko.
In an alternate timeline in the game Star Trek: Armada, the Borg succeed in conquering the Alpha Quadrant. Using a clone of Locutus, the Borg manage to assimilate Spock, kill Worf, and assimilate Earth. The timeline was reset thanks to Jean-Luc Picard and the crew of the Enterprise-E, who travel back in time with the aid of a ship from the future to prevent Spock's capture.
In the game Star Trek: Legacy, an alternate explanation was given to the creation of the Borg which states that the probe V'ger created the Collective to serve as its heralds in its search for knowledge. However, the creation of the Borg Queen resulted in the creation of an entity that abandoned the original intent of V'ger. This is also similar to the Shatnerverse version of events.
In the current volumes of the Next Generation Relaunch series of novels, the Borg have been driven to near extinction as a result of the Starship Voyager's destruction of the Queen and the transwarp conduit network. However, they begin to reconstruct the Collective by building a massive cube in the Alpha Quadrant, in order to launch a vengeful new offensive against the Federation; their first strike results in the assimilation of Admiral Janeway and the destruction of Pluto before the Enterprise-E manages to destroy the cube with the original Doomsday Machine.
In Star Trek: Destiny a history of the Borg was presented. They were survivors of the Caeliar Gestalt and the crew of the Earth ship Columbia NX-02 thrown back in time and into the Delta Quadrant following an attack on a Caeliar city ship. The Caeliar forced the Humans into a perverted form of their Gestalt (a mental linking of the Caeliar) based upon the will of the last surviving Caeliar and not the whole. They launched a final attack of Federation space with over 7,000 cubes at their disposal; however, they were stopped after the Caeliar were made aware of their responsibility for the Borg's actions. The Collective was dismantled and the assimilated Borg drones were accepted into the Caeliar's gestalt. Former drones fully regained their individuality (as evidenced by Seven of Nine's remaining implants dematerializing). This was followed up in the novel Full Circle. Q later noted that this timeline's invasion was provoked by Admiral Janeway's trip to the past in "Endgame", reflecting that, if she had done nothing, the Borg would have eventually launched a massive assault on the Milky Way galaxy centuries in the future that would have completely assimilated all other life. The Voyager relaunch novel Unworthy explores the aftermath of the destruction of the Borg, including some Federation scientists trying to harness remaining Borg technology and Voyager encountering a vast fleet called the "Indign" consisting of species who actually wanted to be assimilated but were considered unworthy of that "honor" by the Borg.
In the Star Trek: The Original Series short story "The Trouble with Borg Tribbles" from the anthology book Strange New Worlds V, a Borg cube encountered a pod full of Tribbles which had traveled through a micro-wormhole from the Alpha Quadrant in early 2268. This was the Borg's first contact with life from that part of the galaxy. The Borg assimilated the surviving Tribbles, only to find that their instinctive drive to eat and procreate was starting to overwhelm the hive mind, causing a widespread series of malfunctions.
The comic book series Star Trek: Countdown shows that Nero's ship, the Narada, was enhanced with a mixture of Romulan and Borg technology. The sequel miniseries Star Trek: Nero has the Borg, the Narada and V'ger originating from an unknown civilization on the "machine planet" that was seen inside V'ger in Star Trek: The Motion Picture.
The Star Trek: The Manga story "Side Effects" in Shinsei Shinsei provided a different story to the creation of the Borg, with an experiment gone wrong to save a race through the daughter of one of the 1,000 or so survivors. Cybernetic implants, along with DNA from nine different species designed to keep a disease from spreading caused the girl to go insane and gain a twisted idea of saving her people. However, the intervention of Captain James T. Kirk made the situation even worse, as the laboratory where she was augmented collapsed and was sucked into a black hole. But, an escape pod with the girl was launched, and apparently catapulted far into the past by the slingshot effect, where her cybernetic implants and DNA evolved to where she became the very first Borg Queen.
In the game Star Trek Online, the Borg have resurfaced after thirty years and have conquered several Federation sectors, including the Mutara sector. The Borg of 2409 look much more like zombies, with some of their cybernetic implants looking like bones coming out of their bodies.
The comic book crossover series Star Trek: The Next Generation - Doctor Who: Assimilation² involves a plotline in which the Cybermen of the Doctor Who universe alter time and space in order to form an alliance with the Borg. The united cyborg force proves to be a devastating threat to the Federation, but the two races end up turning against each other, with the Cybermen going to war with the Borg and forcing the crew of the Enterprise-D and the Eleventh Doctor and his companions to ally with the Borg to restore the Collective and vanquish the Cybermen. At the end of the series, the Borg start to investigate time travel in order to find a way to assimilate the Doctor.
In The Delta Anomaly, a book set in the alternate reality created by the Romulan Nero's attack on the USS Kelvin, the serial killer known as The Doctor (β) is suggested to be related to the Borg. This therefore establishes an earlier contact with Earth than in the prime reality.
In Star Trek: Boldly Go, a comic series also set in the alternate reality and after the events of Star Trek Beyond, the Borg make an appearance as the villain in the first arc of the series, seeking the Narada due to their awareness of its ties to the Borg. They attempt to assimilate Spock, but the primitive assimilation of this era is unable to cope with his hybrid DNA. The shock of his escape and the retrieval of other near-assimilated officers enables the Federation and the Romulans to destroy the Borg.