The drunken head of a Klingon Great House, who in 2371 lunges at Quark over an unpaid bar bill, falls on his own blade and dies, leaving Quark to claim the kill.
Kozak is a Klingon who appears in the opening scenes of the third-season Deep Space Nine episode The House of Quark. Refused further credit, he attacks Quark, stumbles and is fatally stabbed by his own knife. Quark, seeing a chance to bring customers back, tells everyone that he won a fight to the death.
The boast has consequences. Kozak leaves a widow, Grilka, and no male heir, and his enemy D'Ghor wants the house's lands and titles. Since an accidental death would bring dishonour and a death in combat would not, both sides have reasons to press Quark about what happened.
Grilka forces Quark to marry her, making the house briefly the House of Quark, and he exposes D'Ghor's financial attack on Kozak before the High Council.