Koloth was a famous Klingon officer who had appeared in the original series of Star Trek in the episode "The Trouble With Tribbles". He also appeared in the Deep Space Nine episode "Blood Oath". In both these appearances, he was portrayed by William Campbell.
In the DS9 episode "Blood Oath", Koloth and fellow Dahar masters Kang and Kor rendezvoused on Deep Space 9 in preparation for a final confrontation with their mutual enemy, The Albino. As fate would have it, they also encountered Jadzia Dax, the eighth host of the Trill symbiont Dax. Since Dax's former host Curzon was close friends with the Dahar masters, Jadzia was able to convince the three Klingons to allow her to fulfill Curzon's blood oath that he made with them 81 years previously and join them in hunting down the Albino.
During the battle in the Albino's stronghold on Secarus IV, Koloth was fatally wounded by one of the Albino's personal guard. His last words were those of complaint, saying that he refused to die before his friend Kor, the loudest and fattest among their group. Despite his protests, he succumbed to his wound and died, and Kor would be the only one of the three Klingons who survived this adventure.