The Zerg are a vicious alien race from the Starcraft series of video games. They were led by the Overmind, which acted as the swarm's hive mind, and its cerebrates, until the events at the end of the first Starcraft. Afterwards, the swarm were led by Sarah Kerrigan, a human of the Ghost Program who was assimilated into the swarm instead of killed, transforming her into the Queen of Blades.

The Zerg are created at a hatchery, where the larvae are born. The larvae will enter an egg when mutating, evolving upon release into a zerg warrior of some kind. Different zerg types are bred for different purposes. Drones will go through a second mutation, becoming a new, fully organic 'building' used to enhance the strength of the already formidable swarm, while overlords would command sections of the swarm. Zerglings are their basic soldier, rushing the enemy and clawing at them until either side is dead. Hydralisks are the basic ranged infantry of the swarm, spitting acid at the enemy or using its claws to impale a person. Mutalisks can fly above the swarm, provide air support or keeping enemies from taking down the close-combat-based swarm, or it could curl into a cocoon that would split open to reveal a guardian to assist the ground creatures at a cost of its anti-air capabilities, or a devourer which would do the opposite, sacrificing anti-grund to become the ultimate in air superiority. As the swarm evolves, so to do the enemy's chances of survival grow slimmer. The zerg also bear resemblance to other science fiction monsters, including the xenomorphs of the Alien series and tyranids of Warhammer 40k.