(covers information from several alternate timelines)
Porthos was Captain Jonathan Archer's pet Beagle. (ENT: "Broken Bow") One of four puppies in a litter, Porthos and his brothers were named after the main four musketeers from the Alexandre Dumas novel The Three Musketeers: Porthos, Athos, Aramis and D'Artagnan. Porthos and his brothers were born to a female dog owned by the mother of one of Archer's ex-girlfriends. Archer was crazy about the dog and was the first person she called after the dog got pregnant. (ENT: "A Night in Sickbay", "These Are the Voyages...")
When Archer moved aboard Enterprise in April of 2151, he took Porthos with him. Shortly before the vessel departed Earth, Lieutenant Malcolm Reed discussed the ship's transporter with Ensign Travis Mayweather near the craft's transporter platform. Reed was slightly worried when Mayweather told him that the transporter had been approved for bio-transport, but the ensign assured the lieutenant that, from what he had been told, the captain wouldn't even use the contraption on his dog.
In the captain's ready room, Porthos lay with his head on the floor but his legs and torso resting on a mat, while Chief Engineer Charles "Trip" Tucker talked with Captain Archer. Tucker jokingly told Archer that he would be more comfortable with Porthos on the bridge than with the new Vulcan science officer, Sub-Commander T'Pol. Hearing this, Porthos lifted his head up from off the floor and looked towards Archer.
After T'Pol entered, she smelled a scent that disgusted her and glanced at Porthos, realizing that the dog was producing the repulsive odor. Porthos looked back at her shortly before Archer realized that T'Pol, with her sensitive Vulcan sense of smell, was particularly offended by the dog's scent. As T'Pol talked with Archer, Porthos climbed half-way up her leg, wagging his tail excitedly. This encounter made T'Pol flinch and she quickly left the room.
After Enterprise completed its first mission, Archer was attending to Porthos in the captain's ready room when T'Pol and Tucker entered. Porthos sat beside the captain on a large seat, wagging his tail. He licked around his mouth a few times before Archer lifted him down to the floor so that the captain could speak to the officers. (ENT: "Broken Bow")
In May of 2151, Porthos was again in Archer's quarters as the captain made another log entry. While Archer paced back and forth across the floor, Porthos followed on the captain's bed. He was desperately attempting to acquire a piece of cheese that the captain was holding. Archer paused the log entry to reproachfully remind Porthos that he had previously suffered problems digesting cheddar cheese. However, the captain ultimately gave into the dog's pleas. Archer rubbed Porthos behind his ears and resumed the log.
Before the captain left his quarters with Ensign Hoshi Sato, Porthos quietly barked. Archer looked round to see the dog sitting upright, wagging his tail and gazing expectantly at the captain. When Porthos whimpered, Archer reluctantly tossed him another piece of cheddar, informing the dog that it was "the last time". Porthos jumped to catch the cheese in midair and gratefully chewed the snack. (ENT: "Fight or Flight")
Enterprise soon visited a planet that later became known as Archer IV. (ENT: "Strange New World", "In a Mirror, Darkly, Part II") Porthos traveled to the planet in a shuttlepod with a team from Enterprise. He was the first to exit the shuttlepod, bounding out of the craft and racing across the grassy surface of the planet, essentially wasting no time in going – as Commander Tucker put it – "where no dog has gone before".
When Archer whistled for the dog to return, Porthos obediently rushed back to the captain and his officers. The team from Enterprise then decided to separate, with Porthos joining Archer, Tucker, and Ensign Mayweather. The dog ran beside the Humans as they leisurely explored the planet. Porthos eventually raced ahead of his companions to the edge of a small boulder overlooking a stream. He gazed at his surroundings as the Humans took up a position directly behind him and contacted the other members of the team. They soon began to leave the area and Porthos followed them back to the shuttlepod. It was decided there that Archer and Porthos would return to Enterprise while the others would stay on the planet to conduct research and enjoy shore leave. (ENT: "Strange New World")
Shortly thereafter, a group of Borothan pilgrims were hosted aboard Enterprise. Archer entered his quarters after returning from the ship's mess hall to find Porthos barking and whimpering. The captain rubbed the dog behind his ears and assumed Porthos was upset that his breakfast was already two hours late. Archer consequently began to prepare a meal for Porthos, telling the dog that he had also missed his own breakfast. However, Porthos continued to bark and the captain eventually realized that something else was wrong. Archer told Porthos that he wasn't getting any cheese as the captain gave him a bowl of dog food. The Beagle moved away from the food to hide behind Archer and growled at something on the other side of the captain. While Porthos kept snarling, Archer noticed a Borothan robe on his desk. He realized that his pet Beagle had been attempting to warn him that Silik was using his Suliban camouflage ability to hide unseen in the room.
Archer tried to contact ship's security, but was stopped by Silik. After they talked, Silik shot the captain with a Suliban disruptor. Porthos barked in distress as Archer fell to the deck and Silik left the room. Once the Suliban had gone, Porthos whined while he scampered over to Archer's fallen body and licked the captain's face. (ENT: "Cold Front")
Following Archer's recovery, the captain and Commander Tucker took Porthos for a walk in September of 2151. The group left from the captain's quarters and traveled through a corridor to an intercom that Tucker calibrated. As Porthos stood waiting for the Humans, Archer told him to sit. The dog complied with the instruction and continuously wagged his tail. Porthos followed when Archer and Tucker resumed their journey through the corridor. The Humans entered the mess hall together but soon left when T'Pol contacted Archer with news of an imminent emergency.
In engineering, Archer recalled that he had risked the lives of the entire crew by rushing Enterprise out of spacedock. Tucker reminded him that the life of his dog had also been jeopardized and Archer sarcastically replied "Thanks". (ENT: "Silent Enemy")
Shortly thereafter, Captain Archer took Porthos to see Dr. Phlox. While the dog sat on a biobed, Archer and Phlox viewed the animal's stomach using a computer monitor. Phlox diagnosed Porthos as having mild gastrointestinal distress. As Archer approached the dog, he commented that Porthos hadn't been himself recently. The Beagle moaned softly when the captain began to rub behind his ears. Phlox explained that the noted difference in the dog's behavior was a result of Archer feeding Porthos cheese. The doctor advised Archer to learn how to deny Porthos what he wanted. The captain relayed the news to Porthos, telling the dog that he was no longer allowed dairy products.
Phlox injected Porthos with a hypospray before Archer picked the dog up from the biobed and into his arms. While the captain stroked behind the dog's head, he apologized for bothering Phlox. The doctor replied that analyzing the dog's condition was no bother and remarked that Porthos had been one of his most co-operative patients on that particular day. As Archer lifted Porthos down to the floor, the captain thanked Phlox. Archer and Porthos headed toward the exit as the captain asked the dog, "See all the trouble you cause?"
The strong relationship between Archer and Porthos later inspired Phlox to note in a letter to Dr. Jeremy Lucas that Humans surprisingly tended to make intimate bonds with 'lesser' creatures. Phlox was also amused by Archer's habit of anthropomorphizing and even talking to Porthos, although the doctor was fairly certain that the dog could not understand English. Phlox then recalled how he himself had occasionally talked to his Pyrithian bat and realized that speaking to animals was not so strange as he had initially thought. (ENT: "Dear Doctor")
When a group of Ferengi marauders rendered the Enterprise crew unconscious and boarded the ship, one of the aliens named Grish attempted to establish communication with Porthos through a universal translator. After failing to lock onto the dog's language, Grish's cohort, Muk, deduced that Porthos was a lower lifeform and called Grish a fool. Although Muk suspected that the animal was probably the captain's next meal, Grish argued that the size of the dog's ears suggested otherwise. Muk informed his accomplice that he would be able to acquire several bars of gold-pressed latinum for Porthos at the Malurzian Zoo. Muk picked the dog up from off Archer's bed and held him in mid-air while Grish left with another Ferengi marauder named Ulis. Muk subsequently carried Porthos to the launch bay and placed him inside a cargo container.
While a Kantare female named Liana visited the ship, Commander Tucker gave her a tour of the vessel. In engineering, he told her about T'Pol, Phlox, and Porthos. Liana did not understand what a dog was, as she had never seen one and the word had no equivalent in the Kantare language. Tucker therefore described Porthos as a mammal with four legs and big ears. The engineer also commented that the dog was slightly "cute". When Liana asked what Porthos did, Tucker replied, "Not much – he's the captain's pet". Liana understood the word "pet" and realized her mistake. She asked Tucker if she could see the dog, as she was unfamiliar with the creature. (ENT: "Oasis")
In early 2152, Porthos was lying on a cushion in Archer's quarters when he sensed an alien symbiotic lifeform move through a Jefferies tube above the room. He looked up at the ceiling before licking the point of his nose as he quickly moved off the cushion. He then jumped onto the captain's bed and, balancing on his hind legs, began to bark at the ceiling. (ENT: "Vox Sola")
In February of the same year, Archer was lying on his bed and playfully massaging Porthos' head when T'Pol solemnly entered the captain's quarters. Archer held Porthos in his hands and started to gently rub the dog as he asked T'Pol if there was something wrong. When she replied that she had spoken to V'Lar, a visiting Vulcan ambassador, Archer lifted Porthos on to his bed and instructed the dog, "Go on". Porthos then walked to the edge of the bed and jumped down off it. (ENT: "Fallen Hero")
On February 12th, Archer recorded a log entry concerning the crew's forthcoming shore leave on Risa. Porthos lay on the cushion next to the captain's bed and watched as Archer made the entry. When T'Pol contacted the captain from the bridge, he paused the log to answer. She notified him that Enterprise was receiving an incoming distress call and asked whether the bridge crew should alter their course to investigate the emergency. Archer was at first hesitant but eventually replied positively. After closing the communication channel, Archer told Porthos that his walk on the beach would probably have to wait. Aware that his owner was talking about the walk, Porthos barked softly as he jumped up to a sitting position. After Archer left the room, however, Porthos seemed disappointed and depressed. He tucked one leg under him and lay back down. (ENT: "Desert Crossing")
Six days later, Enterprise finally reached Risa. Porthos yipped as he walked through a corridor beside T'Pol and Archer. The captain looked down to check the dog was safe. Satisfied that Porthos was fine, Archer turned his attention to T'Pol and discussed the next two days in which he and his dog would be away. When the group arrived at a turbolift, T'Pol and Porthos entered the lift and waited for Archer to follow them. The captain cocked his head at Porthos before walking into the lift. They traveled to the launch bay, where Archer held Porthos in one arm. The captain talked with Ensign Sato and Crewman Rostov before leaving the ship with Porthos in a shuttlepod. On the way down to the planet, the vacationing officers discussed their plans for the next two days. Archer revealed that he and Porthos were going to relax at a small villa overlooking the Risian ocean. When the captain mentioned Porthos, the dog jumped up on to its hind legs and placed its front paws on the captain's lap. Archer moved one hand behind Porthos and affectionately rubbed the back of the dog's head.
After the captain and Porthos entered their villa, the dog stood on its hind legs near a table. Archer asked Porthos what he thought of the building and commented that the place was "not bad". The dog looked at Archer as he intentionally dropped a water polo bag on a seat. The captain soon noticed a book from T'Pol entitled, The Teachings of Surak, on the table near Porthos. When he put the book back down, Porthos moved away from the table. Archer quickly rubbed the dog's back and headed onto a balcony outside.
That night, Archer read The Teachings of Surak on the balcony while Porthos lay on a chair next to the captain's seat with his head resting on his paws. When Archer got up to pour himself a drink, Porthos lifted his head to watch the captain leave the balcony. The dog dropped its head back to its paws but immediately bolted upright when it suddenly heard two loud, squeaky barks. As Archer poured his drink, he heard the barks mixed with similar noises coming from Porthos outside. The captain returned to the balcony, where he found Porthos with another dog, Rhylo, quite similar to an Earth Chinese Crested breed dog that he had previously seen on a veranda downstairs. As Porthos growled at the other dog, Archer told them both to stop threatening each other. Porthos barked and Archer reprovingly uttered the animal's name, but the dog kept growling.
When the captain heard his front door chime, he picked Porthos up in his arms. The Beagle stopped growling after the captain lifted it away from the other dog. He then carried Porthos to the door, where he met Keyla, the owner of the other dog. She apologized to Archer for her pet's intrusion before he allowed her to retrieve the animal. Porthos watched the visitor as Archer rubbed his head and Keyla made her way to the balcony. The captain followed her outside while he continued to hold Porthos. Keyla picked her own dog up and stated that she hoped her pet had caused Archer's dog no harm. When the captain told her Porthos' name, she said hello to the Beagle. The two dogs glimpsed at one another while their owners held and comforted them, occasionally rubbing the animals softly. Archer told Keyla that he had decided to read and to let Porthos run on the beach. The group went back inside before Keyla said goodbye to Porthos and left.
Archer later discovered that Keyla was a Tandaran and believed that she was an agent of Colonel Grat. When confronted with this discovery, Keyla knocked Archer unconscious and disappeared. The next morning, Porthos licked the captain's face and he eventually regained consciousness.
After a shuttlepod from Enterprise apparently caused the destruction of an alien colony, Archer sat in his quarters sadly looking at a computer record of the colonists as Porthos sat in his lap. He gently rubbed the dog's ears but set Porthos down on the deck before answering an incoming call from Admiral Forrest.
Porthos later lay on his side atop the cushion next to Archer's bed as the captain played with a yellow ball and a game of water polo was shown on the nearby computer monitor. T'Pol entered and, while she spoke about the recent devastation of the colony with Archer, Porthos moved to lie on his torso. The captain bent down next to Porthos as he told T'Pol that he was not only feeling sorry for himself but also for the entire Starfleet.
The dog was still lying on the cushion after T'Pol left. Archer had readied himself for bed and dressed down to his underwear. Porthos looked up at the captain as Archer told the dog that it was time for bed and rubbed behind its ears. After the captain lay down on his bed and switched the light off, he sighed and instructed Porthos to jump up to the bunk but nothing happened. Archer began to ask the beagle what was wrong as he reached for the light but stopped in mid-sentence when he realized he had been transported to an entirely different time and location: Earth, ten months into the past, to the night before Archer and Tucker's inspection by pod of Enterprise prior to launch for another test flight.
Porthos was lying in a soft basket beside Archer's bed. He stirred as Archer answered a call from Commander Tucker. After the captain ended his conversation with the engineer, he looked at Porthos and declared that he doubted the supposed evidence that his time aboard Enterprise had been nothing but a dream. The dog soon sat up in the basket and watched Archer walk to a computer monitor on his desk. Porthos also moved agitatedly when Daniels, an operative from the future, suddenly appeared in the room.
The captain's emotional attachment to Porthos was evident before leaving Enterprise for a Cabal vessel. His last order before he left the ship was for Ensign Sato to care for Porthos and to make sure that the dog had no cheese while he was away. (ENT: "Shockwave")
After Archer returned, Enterprise journeyed to the Kreetassan homeworld and remained in orbit of the planet for five days. An away team consisting of Archer, T'Pol, Porthos, and Ensign Sato eventually took a shuttlepod to the planet's surface and were made to wait there. Unknown to the members of the away team, Porthos was infected with a deadly pathogen on the planet. After the group had waited for twelve hours, the Kreetassans instructed them to return to Enterprise. The away team assumed that they had accidentally offended the Kreetassans and the captain was irritated by the aliens' hypersensitivity but ultimately complied with their request and left the planet with his officers and Porthos.
The Kreetassan pathogen necessitated Dr. Phlox having to replace his pituitary gland with that of a Calrissian chameleon in a complex underwater operation. Thanks to Phlox's skills, Porthos made a full recovery. (ENT: "A Night in Sickbay")
Archer also brought Porthos along when the Enterprise embarked on the search for the Xindi weapon. Tucker worried how Porthos would hold up in the Delphic Expanse, observing that "if no people have returned from the Expanse, I doubt any dogs have." (ENT: "The Expanse")
Porthos was able to sense the approach of spatial anomalies in the Delphic Expanse. Early in the Xindi mission, Porthos attempted to alert Archer of an imminent anomaly. The captain, however, did not understand the warning until after the anomaly had passed through his desk. (ENT: "Anomaly (ENT)")
After the operation, Phlox became quite fond of him, and Archer entrusted the Denobulan with Porthos' safety on a number of occasions. Two of the most notable were when Archer volunteered to become a ritualistic sacrifice for the Triannon, (ENT: "Chosen Realm") and when Archer had to turn over control of the ship to Phlox as it passed through a region of space which negatively affected all Human crew members. While Phlox was the acting captain of Enterprise, he bonded with Porthos to a significant degree, and took time to make a casual study of Human-canine interaction. During this period with a "substitute master," Porthos was unusually fed leeches and appeared to eagerly enjoy them. However, it should also be noted that Porthos appeared to chew the leeches before swallowing; presumably in order to perform their cleansing function, the leeches needed to be alive and undamaged. (ENT: "Doctor's Orders")
Phlox again looked after Porthos when Archer and the rest of the Enterprise crew had to be rendered comatose while the ship traversed a region of space affected by a transdimensional disturbance. However, it was revealed that Phlox's Denobulan physiology was not immune to the effects of the disturbance as he previously thought, and the doctor began to hallucinate to the point where he nearly shot Porthos with a phase-pistol. (ENT: "Doctor's Orders")
After Captain Archer was found alive and Enterprise returned to Earth, the captain and T'Pol were chased by a wild sehlat on Vulcan. T'Pol compared Porthos to a domesticated sehlat she had kept as a pet in her youth but Archer reminded her that, unlike the seemingly aggressive sehlat, Porthos would not try to eat the captain if he was late with the dog's dinner. (ENT: "The Forge")
Porthos later met Danica Erickson in Archer's quarters aboard Enterprise. Erickson wasn't told the dog's name, but she had learned a lot about him from Archer and correctly assumed he was called Porthos. When he playfully rolled on to his side, Erickson commented that Porthos seemed to have a lot of personality. Archer added that the dog had as big an appetite. Just before Erickson left the ship, she asked Archer to say goodbye to Porthos for her. (ENT: "Daedalus")
At one point in November of 2154, Porthos was in Archer's quarters with the captain and Ensign Hoshi Sato. He watched the Humans role-play that Sato was a Tellarite ambassador, the officers' attempt to prepare for the real ambassador's visit aboard the ship. While playing the role, Sato told Archer that his "mangy pet," referring to Porthos, would probably taste better than the food served aboard Enterprise. Once they had stopped role-playing, Sato told the captain that she actually did believe there was some truth to what she had said about Porthos. Archer initially thought she was implying that he was "mangy," but Sato clarified that Tellarites considered canine a delicacy and suggested that the captain keep Porthos out of sight during their stay. (ENT: "Babel One")
Later that month, Dr. Phlox was captured by Rigelians working for the Klingon Empire and forcefully taken to Qu'Vat Colony. (ENT: "Affliction") In Archer's quarters, the captain tried to comfort a miserable Porthos, who lay on Archer's bed. The captain realized that Porthos was either missing Phlox or depressed by the fact that the doctor had a stash of cheese in sickbay. Archer told Porthos to "hold that thought" before answering an incoming hail from Section 31 operative Harris. Porthos watched as Harris told Archer that Phlox was on a mission of vital importance to Starfleet and advised the captain not to interfere. (ENT: "Divergence")
2161 and 2370
In 2161, shortly before Enterprise was decommissioned, Porthos was in Archer's quarters while the captain and T'Pol discussed a final meal for the crew that Chef was preparing. After T'Pol left the room, Porthos jumped on to Archer's bed, whimpered and quickly licked around his own mouth. Archer rubbed behind the dog's ears and assured Porthos that Chef had promised to include six kinds of cheese. Porthos then affectionately licked Archer's nose.
In 2370, Commander William T. Riker watched a re-enactment of this scene in a holodeck aboard the USS Enterprise-D. While later visiting the re-creation of the NX-class Enterprise with Counselor Deanna Troi, Riker recalled that Archer had owned a dog. Troi remembered that the dog's name had been Porthos and that one of the musketeers had been called the same name. (ENT: "These Are the Voyages...")
In an alternate timeline, Archer was relieved of command of Enterprise in 2153 after parasites from a spatial anomaly made him unable to form long-term memories. Months after the incident, one of the few tasks he would still do would be to regularly take Porthos for walks. When T'Pol once visited the former captain, Porthos sat on Archer's bed. (ENT: "Twilight")
Shortly after Enterprise traveled to 1944 of an alternate timeline, Porthos was in Enterprise's sickbay when Doctor Phlox tried to feed him a concoction of his favorite meal, chicken liver, mixed with grated cheddar. As Archer was believed to have died aboard the Xindi weapon, Porthos seemed extremely saddened and refused to taste the food presented to him. When Phlox offered to sing him a Denobulan lullaby, he crawled away from the doctor. Phlox then rubbed his back and suggested that he might enjoy a steak. Porthos reacted by licking his lips and gazing quickly at his surroundings, looking first at the Denobulan doctor. As Phlox left Porthos, he stated that he was going to find Chef.
When Archer later entered sickbay, Porthos jumped up to his leg with a yelp, enormously excited to be reunited with the captain. Archer responded by rubbing Porthos' head. He told Phlox that the doctor would never have to look after Porthos again. However, the Denobulan replied that, as always, he had enjoyed caring for the dog. (ENT: "Storm Front")
Captain Archer regularly provided Porthos with dog food. This was stored in foil-wrapped packets that Archer poured into a bowl and gave to the dog. (ENT: "Unexpected", "Cold Front") Porthos whimpered and complained to the captain if he missed any of his meals. (ENT: "Cold Front") The dog was fond of cheese, although it occasionally caused him to visit Dr. Phlox (in sickbay) for gastrointestinal distress. (ENT: "Fight or Flight", "Dear Doctor")
- "Broken Bow" (Season 1)
- "Fight or Flight"
- "Strange New World"
- "Fortunate Son"
- "Cold Front"
- "Silent Enemy"
- "Dear Doctor"
- "Vox Sola"
- "Fallen Hero"
- "Desert Crossing"
- "Two Days and Two Nights"
- "Dead Stop" (Season 2)
- "A Night in Sickbay"
- "The Seventh"
- "The Catwalk"
- "Anomaly (ENT)" (Season 3)
- "Carpenter Street"
- "Chosen Realm"
- "Doctor's Orders"
- "Azati Prime"
- "The Council"
- "Zero Hour"
- "Storm Front" (Season 4)
- "Babel One"
- "These Are the Voyages..." (hologram)
In a commentary track for "Broken Bow" available on the ENT Season 1 DVD and Blu-ray, Brannon Braga recalls that he and Rick Berman had always wanted to have a dog as a character, so to speak, that appeared regularly. However, they had been extremely worried that there could be a backlash against their decision to finally include a dog in a Star Trek series.
Rick Berman later recalled the casting sessions for the role of Porthos as the most fun of the necessary auditions before filming could begin. Several breeds of dog were tested before production personnel eventually chose to use a beagle.
Prada was eventually cast as Porthos and played the role from "Broken Bow" up to and including "Two Days and Two Nights". Some episodes of Season 1 required a more "spunky" beagle to play the role of Porthos. Although Enterprise's resident dog was male, a female beagle named Breezy was used for these episodes as she had a more playful nature than Prada did. After "Two Days and Two Nights", Breezy and another female beagle named Windy took over the role. Due to strict welfare rules governing the use of animals on television and the expense of regularly having a dog on set, a couple of prop dogs were constructed early in the series to stand in for the real animals. These were still in use in Season 3 and one appeared in "Twilight".
The prosthetic Porthos figures seen in the episode "A Night in Sickbay" – one suspended in the super-hydration tank and one resting inside the quarantine tank – were designed and constructed by Joel Harlow.
Porthos featured in two scenes that were written for the Season 3 episode "Twilight", but neither scene made it into the final show. Both scenes take place in an alternate timeline. One scene, which is set in the mess hall during the crew's regular movie night, shows Archer informing T'Pol that Porthos has recently seemed frequently stressed and might benefit from Vulcan neuro-pressure. In the other scene, Porthos appears but is fifteen years older.
In the final draft script of "Carpenter Street", Porthos was featured in a short scene that does not appear in the final version of that episode. In it, Porthos was lying in Archer's quarters, late at night, but picked up his head when Archer offered him a treat. This scene was immediately before one that was not only in the script but is also in the final edit of the installment, in which Porthos is treated to some cheese Archer gives him in Enterprise's galley.
Brannon Braga ultimately came to the decision that all of the viewers and production personnel had grown to like or accept Porthos.
Perhaps as a result of his popularity, Porthos was the only character, besides the regulars, to appear in both the first and last episodes of Star Trek: Enterprise.
Porthos is the fourth of six recurring animals throughout Star Trek, the others being Livingston, the fish belonging to Jean-Luc Picard, Data's cat Spot in Star Trek: The Next Generation, Chester, a cat owned by Miles O'Brien in Star Trek: Deep Space Nine, Number One, Picard's dog in Star Trek: Picard, and Grudge, Cleveland Booker's cat in Star Trek: Discovery.
Porthos is indirectly referenced in Star Trek, when Montgomery Scott mentions "Admiral Archer's prized Beagle". Screenwriter Roberto Orci, responding to a question about whether this was Porthos (and whether veterinary science had advanced enough for a dog to live over a hundred years), answered "YES!" It should be noted, however, that the individual who asked the question pleaded for the writer to "please say yes." 
Along with Shran, Ambassador Soval, and Daniels, Porthos is one of only four characters, outside of the main ones, to appear in all four seasons of Star Trek: Enterprise. Of those four, Porthos is the only one to appear in more than one episode of each season.
The It's A Wrap! sale and auction auctioned off a bulletin board, similar to those created for other main characters, that was apparently dedicated to Porthos. . If it appeared on screen, it is unclear where. It included a number of jokes.
In the novelization of The Expanse, it is said that Porthos was originally given to Archer from Becky's mother, having been bred as part of one of her prize litters, and that she was also responsible for naming the dog (as well as his brothers).
The Star Trek: Waypoint, Issue 4 story "The Fragile Beauty of Loyalty" sees Porthos volunteer to travel back in time to Archer's childhood and rescue him after young Archer falls through the ice, following a Temporal Cold War attempt to kill him before he reaches adulthood.
In the novel Patterns of Interference Porthos died due to old age in March of 2166, with Archer at his side.