Cerberus (Resident Evil Zero)

Cerberus, essentially a Doberman infected with the T-Virus, is thankfully not a common enemy in the game. They've taken residence is the forest surrounding the Spencer Mansion. Despite the rotting skin and muscle hanging off their bones, they're still surprisingly quick, the virus giving these creatures an insane lust for blood. They'll dive for your arm the first chance they get.

Although quick, they are easy to keep at bay with the Handgun. The worst problem with these is if you manage to get in between two of them, then you have no choice but to run to a better position.