Centaurs were created by the Master. The creation process involved tossing a varied mix of humans, dogs, and other types of animals into a Forced Evolutionary Virus nutrient vat to be infected by the virus, and then see what mutant chimera emerged as the virus produced rapid and unpredictable mutations. As a result, centaurs can differ quite radically in physical appearance from one another. However, all known centaurs are somewhat humanoid in appearance.
Physically, they are around the size of a bear, with a large, misshapen torso and six humanoid arms that serve as legs. A cluster of wriggling fleshy tentacles bloom out from their underside, scrabbling at the ground around them. Branching from their front halves are a pair of long, thick necks, with a canine head on the right and a humanoid one on the left. The canine head has a thick metal collar around its neck adorned with spikes, not unlike an ordinary dog collar.
Both heads seem to be capable of individual thought, as the dog head can be seen snapping at the human head. Centaurs are not only created by the FEV, they also seem to live quite successfully in a heavily irradiated environment.
Centaurs frequently travel in packs with floaters. They encompassed a large bulk of the Master's armies and are commonly found with the nightkin and other remnants of the Master's army who roam Northern California.