From The TimeSplitters Wiki

Carrion Carcass is a character in Timesplitters Future Perfect. It resembles the corpse of a dead cow, with it's stomach ripped open and it's inards ripped out.

It can be found on the level "Mansion of madness" where you have to defeat an entire room full of them.

Aracde

When selected in Arcade mode, Carrion Carcass leaps off the floor, and starts mooing manically.