"Long live the Empire!"
– Kor's last words, 2375 ("Once More Unto the Breach")

Dahar Master Kor, son of Rynar was a male Klingon military officer and ambassador in the 23rd and 24th centuries. He was among the most influential warriors and respected military leaders of the Klingon Empire.

Kor was the last son of the House of Kor and descendant of the Klingon Imperial Family. He also had a son. He was descended from Klingons affected with the augment virus created in 2154, a product of 22nd century Klingon genetic engineering. By the 24th century, he was cosmetically indistinguishable from an average Klingon. (ENT: "Divergence"; DS9: "Blood Oath"; TOS: "Errand of Mercy")

Throughout his illustrious career, Kor played key roles in many legendary battles against the Federation and Romulan Empire. Kor's influence in the Empire eventually elevated him to the status of Klingon Dahar Master. (DS9: "Blood Oath") During his life, he saw the Klingon military changing its name from Klingon Imperial Fleet to Klingon Defense Force.

In 2267, following the breakdown of peace talks between the Federation and the Klingon Empire, the Federation-Klingon War broke out. The neutral planet of Organia, a strategic position between the two powers, became a political hotspot between the Empire and the Federation.

On stardate 3102.7, Commander Kor led a battalion of five hundred Klingon soldiers in an invasion and occupation of Organia, where he briefly became their military governor. As governor, Kor ruthlessly maintained order on the planet, ruling with an iron fist by maintaining a stringent list of rules, any violation of which was punishable by death. Unknown to Kor at the time, Captain Kirk, posing as an Organian, and Lieutenant Commander Spock, posing as a dealer in kevas and trillium, were among the subjugated. The two Starfleet officers mounted vain guerrilla attacks against Kor and his army. Meanwhile, in orbit around Organia, the Klingon and Federation fleets faced each other in battle.

Once the hostilities between the two began to reach its climax, all ships suddenly and mysteriously became paralyzed and all weapons became superheated and temporarily rendered useless. Unknown to both sides at the time, the Organians were in fact an advanced non-corporeal species, despite their primitive way of life. As quickly as it started, the Organians effectively ended the occupation, the war, and Kor's governorship. (TOS: "Errand of Mercy") The Organians continued to promote peace between the two powers by imposing the Organian Peace Treaty. (TOS: "The Trouble with Tribbles")
Within two years, Kor became the commanding officer of the IKS Klothos. In 2269, Kor again faced his enemy, Captain Kirk, in battle when the Klothos engaged the USS Enterprise in the Delta Triangle region. During the battle, the two ships became entangled in a "time trap," a phenomenon unique to that region, pulling the ships into an alternate universe known as Elysia.

Kor attempted to escape but the Klothos was unable to break free from the region, partly due to its unusual properties, including draining dilithium crystals of their energy. Through cooperation, the crews of the Enterprise and Klothos were able to formulate a strategy by combining their warp power in an effort to overcome both ships' individual power deficiencies.

Prior to their attempt, however, Kor had one of his officers, Kali, plant a bomb-like device in the computer room of the Enterprise, set to explode once the starship cleared the phenomenon and reached warp eight. Both ships were able to escape the region, and the destruction of the Enterprise was averted, moments before the ship reached warp eight. Nevertheless, Kor claimed responsibility for formulating their combined escape and returned to Klingon space, no worse for the wear. (TAS: "The Time Trap")

Kor's ship, the Klothos, was one of the first Klingon vessels equipped with a cloaking device. Kor is said to have spent three days in the engine room taking it apart and studying it before their first mission. This proved critical when he later commanded one of the two Klingon divisions aboard the Klothos, along with Kang, in an attack against the Federation outpost at Caleb IV. During the attack, Kor successfully tricked his opponent by launching first a small initial attack, and then striking with the bulk of his forces when the Federation began repair efforts. (DS9: "Once More Unto the Breach")

Kor was involved in several combative entanglements with the Romulan Star Empire. In 2271, Kor led the Klingon Empire to a glorious victory over the Romulans, at the legendary Battle of Klach D'kel Brakt. Kor liked recreating the battle so much that he called it up each time he went to the holodeck. On one occasion before he went on his quest to kill The Albino he was playing this battle in the holosuite and he got so drunk with Breshtanti ale that Odo had to put him in a holding cell to sleep it off. (DS9: "Blood Oath") Worf once recalled a story he had heard about Kor during his own childhood, which described Kor's "attack on Romulus." (DS9: "The Sword of Kahless")

Kor, with fellow warriors Koloth and Kang, held the Korma Pass against T'nag's army in a glorious battle in a trinary star system, where they 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")

Kor became a close friend to Curzon Dax, the Federation ambassador to Qo'noS, in 2289. In one of their escapades, Kor and Dax broke into the Duke's harem on Renavi. In 2370, when Kor and Jadzia Dax, Curzon's successor, were reunited, Dax knew Kor well enough to recall that he had a scorcher burn on his fourteenth rib, and that his left QiVon ached every time his ship hit warp eight. (DS9: "Once More Unto the Breach", "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, as they captured 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 the space of a few years, he kept his word and managed to infect the warriors' three innocent children with a genetic virus that eventually killed them all. (DS9: "Blood Oath")

In 2290, Kor, Kang, Koloth and Curzon Dax pledged a blood oath to avenge the deaths of the Klingons' sons, 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 contacted 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. Koloth was fatally wounded fighting the Albino's personal guard. Following a fierce duel, Kang was able to slay the Albino (held at bay by Dax) before he died as well. Having fulfilled their blood oath, both Kang and Koloth died glorious and honorable deaths. (DS9: "Blood Oath")