Gamma Quadrant alien bred to be the prey in a ritual hunt, whom Miles O'Brien helped escape from Deep Space Nine.
Tosk is a visitor from the Gamma Quadrant who arrives at Deep Space Nine in a damaged ship. He is a member of a species bred to be hunted, his life devoted to evading the Hunters who pursue him for sport, and he befriends Miles O'Brien while hiding on the station.
In Captive Pursuit, the Hunters arrive and demand Tosk's return. Benjamin Sisko feels bound by the Prime Directive to hand him over, but O'Brien, who has grown to respect him, overpowers a Hunter at an airlock and helps Tosk escape the station to resume the hunt on his own terms.