As a product of 22nd century genetic engineering, Koloth was descended from Klingons affected with the augment virus created in 2154. By the 24th century, he seemed to have been cured or cosmetically altered. (ENT: "Divergence"; TOS: "The Trouble with Tribbles"; DS9: "Blood Oath"; DS9: "Trials and Tribble-ations")
Koloth's status within the Empire was revered to the extent that he achieved the status of a Klingon Dahar Master. His glory would further succeed 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")
Much of Koloth's early career is unknown, however, by the 2260s, he had achieved the rank of captain and was assigned as commander of D7 class battle cruiser IKS Gr'oth. (DS9: "Trials and Tribble-ations")
In 2268, the Gr'oth was on a six-month mission, assigned to patrol the border of the Klingon Neutral Zone. Around stardate 4523.3, Koloth ordered the Gr'oth to stop at the Federation Deep Space Station K-7, to claim shore leave rights. Shore leave was accepted, however, shortly thereafter, a brawl between his crew, precipitated by his first officer Korax, and a group of Starfleet officers on the station broke out. Koloth demanded that Captain Kirk issue a formal apology and assume full responsibility for the "persecution" of Klingon nationals in the quadrant. Kirk, however, refused, citing a recently-discovered Klingon plot to poison a shipment of grain destined for Sherman's Planet. (TOS: "The Trouble with Tribbles"; DS9: "Trials and Tribble-ations")
In 2269, Koloth pursued a Federation scoutship piloted by Cyrano Jones, a Federation citizen who was responsible for causing ecological sabotage to a Klingon planet and stealing a Klingon glommer. Koloth encountered and attacked the USS Enterprise, under Kirk's command, in order to retrieve Jones and the glommer. (TAS: "More Tribbles, More Troubles")
Koloth, Kor and Kang, 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 2289, Koloth represented the Klingon Empire in the negotiations at the Korvat colony with the Federation. Koloth had little use for the Federation, and his implacable demeanor towards their top ambassador, Curzon Dax, earned him the nickname d'akturak or "ice-man". No matter how reasonable the proposal, or how much it favored the Klingon Empire, Koloth was never satisfied. (DS9: "Blood Oath")
During the late-2280s, a band of depredators, led by the Albino, began raiding Klingon colonies. Three Klingon warships, led by Kor, Koloth and Kang, 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, he 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 the sons of the three Klingon captains, the offense committed by the Albino. They nearly caught him at Galdonterre, but one of their subspace messages was intercepted and he, once again, was able to escape.
After decades of searching, Kang learned of the whereabouts of the Albino, in 2370, on the planet Secarus IV. Kang traveled to Secarus IV and discovered his compound. The Albino knew immediately of his arrival and invited the trio to a "fair fight" and one last glorious battle. Kang would contact both Kor and Koloth for a rendezvous on Deep Space 9, in preparation of their final attempt to complete their lifelong quest.
Three months later, Kor, Koloth, and Kang, with the aid of Jadzia Dax, prepared their attack on the Albino's compound, only to discover that it was a trap. Using the element of surprise, they bombarded the compound with tetryon particles, forcing the Albino and his sentries into face-to-face, hand-to-hand combat. Following a fierce battle, the mortally wounded Kang was able to slay the Albino. Fulfilling their blood oath, both Kang and Koloth were able to die a glorious and honorable death. (DS9: "Blood Oath")
Koloth was played by William Campbell, and was voiced by James Doohan in Star Trek: The Animated Series. Koloth was supposed to become a continuing Klingon character-as a foil for Kirk, in many episodes, according to The Making of Star Trek, but nothing came of that idea afterwards.