Cerberus

Cerberus (also called Hell-Hound) is a three headed dog-like beast that can be seen in the background of the Netherrealm arena of Mortal Kombat(2011).

Trivia

 * A Cerberus is alike to the Netherrealm Hound. Only difference is that The Netherrealm Hound does not appear in Mortal Kombat (2011). Not to mention it does not have 3 heads.