Kang was among the most influential leaders and feared diplomats in the Klingon Empire during the late 23rd and early 24th centuries. He is known in Federation history for his long friendships with Kor, Koloth, and Curzon Dax, and as an adversary of Starfleet Captain James T. Kirk.
As a product of 22nd century genetic engineering, Kang was descended from Klingons affected with the Klingon augment virus created in 2154. (ENT: "Divergence") By the 2290s, Kang was outwardly cured of this affliction either through medical treatment, cosmetic surgery, or a combination of both. (VOY: "Flashback")
Throughout his illustrious career, Kang played key roles in many legendary battles against the Federation, both on the battlefield and at the negotiation table. As a result of his prowess, Kang's status within the Empire was revered to the extent that he achieved the status of a Klingon Dahar Master. His glory further succeeded him, after his death in 2370, when he earned his own statue among the Hall of Heroes on Qo'noS. (DS9: "Blood Oath", "The Sword of Kahless")
Kang wed his wife, Mara, prior to 2268; she later served as Kang's science officer aboard his battle cruiser during the late 2260s. By 2290, Kang had his first son, whom he named Dax, in honor of his friend, the Federation ambassador to Qo'noS, Curzon Dax. (TOS: "Day of the Dove"; DS9: "Blood Oath")
Conflicts with the Federation
While responding to a distress call at Beta XII-A in 2268, Kang's battle cruiser sustained massive internal damage after the ship became disabled, resulting in the deaths of 400 of his crew. As the ship drifted towards Beta XII-A, Kang beamed down to the planet to discover Captain Kirk on the surface. Kang accused Kirk of attacking his ship and took Kirk prisoner, while claiming the orbiting USS Enterprise for the Klingon Empire.
Kang convinced Kirk to beam the group up to the Enterprise, where he and the remaining thirty-seven survivors were transported aboard as prisoners. Kang's wrecked ship was destroyed by the Enterprise, because of the danger it posed by emitting a massive amount of hazardous radiation.
Aboard the Enterprise, intense fighting broke out between the two groups, as the ship mysteriously hurtled toward the galactic rim. The emergency bulkheads of the Enterprise, soon after, sealed themselves, trapping 392 members of the Enterprise crew below decks.
The entire situation – including the phantom Beta XII-A colony, imaginary distress calls, and transmutation of the weapons aboard the Enterprise – were discovered to have been engineered by an unknown energy being that thrived on the belligerent emotions precipitated from the ingrained hatred between the Klingon Empire and Federation. Through the cooperation of Mara, Kirk was able to cooperate with Kang to drive the lifeform away by generating positive emotions. (TOS: "Day of the Dove")
Relations with the Federation continued to periodically flare up, throughout the latter half of the 23rd century. On one such occasion, Captain Kang, together with Captain Kor, led two divisions of warships in an ancient Earth cavalry-style attack on a Federation outpost at Caleb IV. During the attack, Kang and Kor successfully tricked their opponents by first launching a small initial attack, and then striking with the bulk of the forces when the Federation began repair efforts. (DS9: "Once More Unto the Breach")
Kang, Koloth, and Kor, who originally set out with forty legions, together held the Korma Pass against T'nag's army in a glorious battle in a trinary star system. The three warriors forced the enemy to fight with the blinding light of three suns in their eyes. The battle ended with the mountainside covered with so many dead that there was not a square meter of ground to be seen. They together feasted on T'nag's heart, in celebration of their victory. (DS9: "The Sword of Kahless", "Once More Unto the Breach")
In 2293, after having met at Beta XII-A, Kang once again encountered Captain Sulu, now in command of the USS Excelsior, in the Azure Nebula, as Sulu attempted a foray into Klingon space. After congratulating Sulu for his well-deserved captaincy, he threatened him to "not let it end prematurely". Sulu claimed to have gotten lost; Kang insisted he escort Excelsior to Federation space, but Sulu was determined to continue his unauthorized mission to rescue Kirk and Dr. Leonard McCoy from Rura Penthe. To evade Kang, Sulu ignited the volatile sirillium gas inside the nebula, which his ship had exited first, disabling Kang's battle cruiser and ensuring the Excelsior's escape. (VOY: "Flashback")
Kang commanded many ships in his career. In 2372, Kang's friend Kor had a dream about discovering the Sword of Kahless. In the dream, the statues of Kang and Koloth in the Hall of Heroes would turn to flesh and blood, as the trio presented the Sword to Emperor Kahless. Kang's ship then decloaked above, a swirl of song transported the trio into its embrace, and the ship streaked away into the golden light to the gates of Sto-vo-kor. (DS9: "The Sword of Kahless")
During the late 2280s, a band of depredators, led by the Albino, began raiding Klingon colonies. Three Klingon warships, commanded by Kang, Koloth, and Kor, were sent out to stop him. Their mission was successful in capturing most of the depredators. However, the Albino was able to escape. In the Albino's last message to the Klingons, he promised to take his revenge on the firstborn of each of the three captains. Within a few years, the Albino kept his word and managed to infect the warriors' three innocent children with a genetic virus that eventually killed them. (DS9: "Blood Oath")
The blood oath
In 2290, Kor, Kang, Koloth, and Curzon Dax pledged a blood oath to avenge the deaths of their sons, the offense committed by the Albino. They nearly caught the Albino at Galdonterre, but one of their subspace messages was intercepted and he, once again, was able to escape.
In 2363, after decades of searching, Kang discovered one of the Albino's discarded wives on Dayos IV. Kang fed and clothed her. He later told her the story of his murdered son and his quest for the Albino. Although she said nothing of the Albino's location, Kang suspected that she knew where he was.
In early 2370, Kang received an amulet, sent to him through the recently deceased former wife of the Albino. The amulet revealed to Kang the whereabouts of the Albino, who had a compound located on Secarus IV. Kang traveled to the Secarus system to confirm the revelation, only to be immediately contacted by the Albino, who, unexpectedly, invited the trio to a "fair fight" and one last glorious battle – forty of the Albino's best warriors against his four pursuers. Not expecting victory but willing to settle for an honorable death in battle, Kang accepted.
Three months later, the Klingons assembled at Deep Space 9, where Dax's then-current host, Lieutenant Jadzia Dax, was assigned. Kang informed the others of the Albino's location but not of what happened when he had gone there. Kang objected to Jadzia's inclusion, believing she was not bound by Curzon's blood oath. Though she convinced Kor and Koloth to support her, Kang continued to resist until he reluctantly relented. En route to Secarus, Dax pressed Kang on the matter until he finally admitted the truth to her and, eventually, the others. It was later discovered that the Albino had never had any intention of honoring his word and had laid a trap by planting a gravitic mine at the threshold of his compound. Dax suggested using the Albino's expectations to their advantage and plan a new strategy.
Using the element of surprise, they bombarded the compound with tetryon particles, rendering any energy-based weapons useless, and forcing the Albino and his sentries into face-to-face, hand-to-hand combat. Koloth was fatally wounded fighting the Albino's personal guard. Kang's bat'leth was shattered during a fierce battle with the Albino and Kang was mortally wounded. However, Kang managed to kill the Albino (held at bay by Dax), by stabbing him in the heart with a d'k tahg, before Kang died as well. Having fulfilled their blood oath, both Kang and Koloth died glorious and honorable deaths. (DS9: "Blood Oath")
According to the script for "Blood Oath", his name was pronounced as "KANG". 
The role of Kang, as written for "Day of the Dove", was actually first intended to be a reappearance of Kor. Once it was determined that Kor actor John Colicos couldn't play the part (much to his frustration), the character's name was changed and a suitable actor was sought. (The Star Trek Interview Book, p. 147; Starlog #164)
Joseph Campanella was nearly accepted for the part of Kang but was rejected out of fears that he wouldn't be able to draw "enough fire." (The Star Trek Interview Book, p. 147; Starlog #164) Next, Michael Ansara was considered to play Kang. Ansara was attracted by the nobility embodied in the role, finding Kang "a magnificent character to play!" He later said, "Immediately, just from reading the script, I knew how special the role was and how rare it was to find a character like this in either television or film." Ansara was also interested in playing Kang because the character reminded him of several of his previous roles, two of which had many of the same qualities as Kang. Ansara was finally cast as Kang and found that appearing as the Klingon in "Day of the Dove" was "a pleasure to do." (Starlog #138, p. 32) The actor tried to avoid turning Kang into a villainous caricature by not thinking of him as evil, just a misunderstood, passionate leader. "When I did that first Star Trek episode," Ansara reflected, "I played Kang as a dynamic character [....] I never thought of Kang as a bad guy – he was doing what he thought was right." (Star Trek Magazine issue 116, pp. 39 & 40)
Michael Ansara portrayed Kang in all of his appearances. Though Ansara would have been willing to return as Kang on Star Trek: The Original Series, that opportunity never presented itself, as the series was canceled shortly after "Day of the Dove" was first broadcast. The performer was disappointed not to be asked back for the subsequent Star Trek films featuring the TOS cast, commenting, "I must admit, I missed seeing myself up there on the big screen as Kang." (Starlog #138, p. 32)
Kang was originally intended to be commemorated, by Robert Hewitt Wolfe, in the naming of a poem called "The Fall of Kang" from the Star Trek: Deep Space Nine episode "Second Sight". In retrospect, Wolfe recalled, "I thought, 'It's been eighty years and he was a real cool guy; he probably went out in a blaze of glory.'" The fact Kang reappeared in DS9: "Blood Oath" later caused the DS9 writing staff to suggest several alternatives to explain how the Kang referenced in the poem was a different person to Michael Ansara's Kang. (Star Trek: Deep Space Nine Companion (p. 104))
Peter Allan Fields, writer of "Blood Oath", based Kang's persona in that episode on Yul Brynner's character of Chris Adams from The Magnificent Seven. When required to reprise the role of Kang in "Blood Oath", Michael Ansara turned out to be an easy find for Deep Space Nine's casting personnel, though he was surprised to be asked back to Star Trek. (Star Trek: Deep Space Nine Companion (pp. 131 & 132)) He was once again thrilled to portray the Klingon, thinking it "still was a good role." (Star Trek: Communicator issue 104, p. 18) On the other hand, Ansara discovered that reviving the role for DS9 "was strange, really strange." Despite the fact that Kang had clearly undergone some physical changes, Ansara still played him as the same character. "I gave him the same kind of voice and personality," the performer explained. "I felt the same way about the character – Kang is a very powerful outer space being." Additionally, owing to the amount of makeup involved, Ansara thought that playing the Klingon again was challenging. "It was a long, hard day every day," the actor critiqued. (Star Trek Magazine issue 116, p. 40) Director Winrich Kolbe decided that Kang's death was to take place at the top of a flight of stairs, but Fields was disappointed that a close-up shot of Kang dying was not used. (Star Trek: Deep Space Nine Companion (pp. 131 & 132))
Even though Kang had appeared in both "Day of the Dove" and "Blood Oath" by the time his involvement in VOY: "Flashback" was devised, that episode's script mentioned only his appearance in "Blood Oath". The scripted scene description for when Kang first appears in "Flashback" stipulated that Kang was to look younger than he had in the DS9 episode.
Some production staffers very much enjoyed Michael Ansara's performances as Kang. Jerome Bixby, who initially conceived Kang, was highly pleased with Ansara's first portrayal of the character in "Day of the Dove", exclaiming, "Ansara's great in it!" and further remarking, "[He] just ate up the part." (Starlog #164; The Star Trek Interview Book, p. 147) Bixby was also interested in being paid a royalty for the reuse of Kang in DS9, commenting, "In the long run that may be more damaging to them because they used the same character. Kang will probably mean some bucks for me." (Captains' Logs Supplemental - The Unauthorized Guide to the New Trek Voyages, p. 74) Fellow Klingon-playing actor Mark Lenard, who featured as a Klingon captain in Star Trek: The Motion Picture, characterized Ansara as "a great Klingon." (Starlog #138, p. 35) Ansara himself considered Kang to be "one of the best characters I've ever played." (Star Trek: Deep Space Nine Companion (p. 131))
Fan response to Kang was extreme. In a 1989 interview, Michael Ansara mused, "What's amazing is that even today, I still get recognized for that part. It is pleasurable and always positive, but surprising. I played that character almost 20 years ago, but people still remember." (Starlog #138, p. 32) The actor once speculated that people responded to Kang because he was a natural leader and because Ansara played him not as a simple bad guy but as an individual who believed in what he was doing. (Star Trek Magazine issue 116, pp. 39 & 41)
"Rage of the Red Lanterns", a 2017 episode of the animated series Justice League Action, contains an homage to Kang. The character of Atrocitus, voiced by Michael Dorn, echoes Kang when he utters the line, "But for today, only a fool fights in a burning house." That animated episode also featured Armin Shimerman.
- Kang is a major character in the novel Pawns and Symbols, in which it is implied that he is not only a prominent starship commander, but also of noble lineage and the heir apparent to the Imperial throne.
- Kang appears in the My Brother's Keeper series, where he is called Kang, son of K'naiah.
- Kang's mirror universe counterpart (β) appeared in the novel The Sorrows of Empire and the novella "The Worst of Both Worlds".