In Greek mythology, Cerberus, often referred to as the hound of Hades, is a multi-headed dog that guards the gates of the Underworld to prevent the dead from leaving. Cerberus was the offspring of the monsters Echidna and Typhon, and is usually described as having three heads, a serpent for a tail, and snakes protruding from multiple parts of his body. Cerberus is primarily known for his capture by Heracles, one of Heracles' twelve labours. I've used a wither model to recreate Cerberus, so you can use this mob skin.

Tips: After you download this mob skin and use it on your world, you will have to summon the wither. At first, it will look just like a regular wither (during it's invulnerable state) but then, when the wither starts attacking you, it will turn into Cerberus (this is because, the wither has two skins - one for the invulnerable state, and the other for the regular state. I have used the regular state). Also, instead of shooting wither skulls at you, it will shoot out lava bombs at you (The wither skull's skin is integrated with the wither's skin).