Zerus is the Zerg homeworld in the StarCraft universe.
The planet is presented as the ancient origin of the Zerg, long before their expansion into the Koprulu Sector. Zerus is a harsh, primal world where the earliest Zerg evolved and where survival depends on constant adaptation and biological competition.
In StarCraft II: Heart of the Swarm, Sarah Kerrigan returns to Zerus during the campaign. The world’s primal Zerg provide important story context, showing that the modern Swarm is connected to older and more instinct-driven forms of Zerg life.
Zerus is often confused with Char, another important Zerg-associated planet. Char serves as a major Zerg base and battlefield, while Zerus is the species’ ancestral homeworld. Aiur, by contrast, is the homeworld of the Protoss.