Kozak was a Klingon male who lived during the 24th century. He was the leader of the House of Kozak, and the husband of Grilka. According to Odo, Kozak was a disreputable character, and a notorious drunkard. Grilka later revealed that Kozak had accumulated a large gambling debt.
In 2371, Kozak had arrived on Deep Space 9, and went to Quark's bar, where he became very drunk. Running out of money he asked to set up a line of credit, but attacked Quark when the Ferengi approached him. During the brief struggle, Kozak tripped and fell on his own d'k tahg.
Seeing a way to boost business, Quark lied to Odo and others about the circumstances of the death, claiming that he was forced to kill Kozak in self defense. Kozak's old enemy D'Ghor tried to use the situation to his advantage, however Grilka and Quark were able to prevent D'Ghor from seizing Kozak's lands and properties. With the unusual circumstances, the Klingon High Council granted Grilka special dispensation, allowing her to lead the family, renamed the House of Grilka. (DS9 episode: "The House of Quark").