Kerrigan first appears in "StarCraft" as a twenty-six-year-old Terran Ghost, a psychic trained both physically and mentally as an expert espionage agent and assassin. Initially the second-in-command of Sons of Korhal, a revolutionary movement against the oppressive Confederacy of Man, she is captured by the insectoid Zerg and "infested" (in-universe term for genetic mutation), turning her into a human/Zerg hybrid completely under the control of the Zerg Overmind. She becomes one of the Zerg's most powerful agents, but during the Brood Wars, she replaces the Overmind following its destruction at the end of the great war, and gains control of the Zerg to seek dominance over the galaxy. Kerrigan's life before her infestation is further explored in the "Starcraft" novels "Uprising" and "Liberty's Crusade", while "Queen of Blades" elaborates on her infested character.