Cerberus (RE films)

"Cerberus" is a codename given to dogs infected with the T-virus in the Resident Evil films. Initially an accidental byproduct of the T-virus outbreak in the Hive, these undead canines would later be used as bio-weapons by the Umbrella Corporation.

Biology
The zombie dogs in the Resident Evil films differ little from the zombie dogs that appear in the video games. When infected with the T-virus, the Doberman hound undergoes severe cellular deterioration, with fur and skin sloughing off the body and bones and organs becoming partially visible. Despite this deterioration, the dog maintains its physical capabilities and can still run and pounce. It becomes increasingly aggressive and will attack any uninfected creatures on sight, consuming their flesh.

During the Global T-Virus Pandemic, Umbrella would attempt to properly weaponize infected dogs, designating them "Cerberus". The experiments would result in new, frightening mutations that resulted in the dogs' heads being able to split open vertically, revealing a grotesque maw filled with fangs and thin tendrils.