The Zerg Swarm is a terrifying and ruthless amalgamation of biologically advanced, arthropodal aliens. Dedicated to the pursuit of genetic perfection, the zerg relentlessly hunt down and assimilate advanced species across the galaxy, incorporating useful genetic code into their own. They are named "the Swarm" per their ability to rapidly create strains, and the relentless assaults they employ to overwhelm their foes.
Alongside the protoss and terrans, the zerg stand as one of the three dominant species of the Milky Way and are universally feared, hated and hunted as such. The Swarm in itself makes up a third of the power of the Koprulu Sector. Zerg remain in areas of the galaxy outside the Koprulu sector.