Cerberus were used as subjects by Umbrella to test the effects of the T-Virus on dogs. They were given the code number MA-39 and were named after the mythological three-headed guardian of Hades. They were seen in the Arklay Research Facility (in Resident Evil) and running loose in the Arklay forest area. Several were also being transported within the Ecliptic Express (in Resident Evil 0) inside the train's Freight Car.