Sheep

Sheep are NPCs in Goat Simulator.

Goat MMO Simulator
Sheep are supposedly the main antagonists in the game, and are also apparently the natural enemy of Goats. They will attack in a similar fashion to goats, headbutting and making sheep noises. They can often be found with the Mutators Rouge, Tank, Hunter, and occasionally Magician. It is also noteworthy that they are never labelled as "Sheep" in battle, only in dialogue. In battle, their individual names are completely randomized from hundreds, and are purposely supposed to come across as funny usernames. They can be found battling Goats outside the Goatshire. Though they can also appear off-path in forests leading to Glarblargle Beach, over a hill near the entrance to Goatwind, around Twistram, and many other places. They can be described by human NPC's as "dastardly" and "thieving scoundrels". They will fight Goats without hesitation, and on occasion, they will also quarrel with Bears. They are able to withstand several direct hits from various attacks, most resistant to NPC Goats. They will respawn in the same places a short while after death.

GoatZ
Sheep are in the goat pen along with the goats. They aren't enemies here, just NPCs.

Waste of Space
Sheep will run away from you if you come too close.