The commander of the Hazari bounty hunters who surround Voyager in 2375, later persuaded by Captain Janeway to turn on the Think Tank that secretly hired him.
Y'Sek appears in the Voyager episode Think Tank. He leads the Hazari ships that box Voyager into a region of space, working methodically to capture the vessel for an unknown client.
Janeway learns that the client is the Think Tank itself, which engineered the hunt so that it could offer rescue in exchange for Seven of Nine. She takes the evidence to Y'Sek and shows him that he has been deceived over who is paying and how much.
Y'Sek agrees to a joint plan. He pretends to go on with the hunt, extracts a better offer from Kurros, and then attacks the Think Tank's ship once Voyager has disrupted its defences.