Mumm Ra

Mumm Ra is a demon-priest and servant to the Ancient Spirits of Evil who provide him with his powers so he can spread their dark influence throughout Third Earth. Mumm-Ra exists in a decayed, mummified  form that must return to a stone sarcophagus to replenish his energy. He can transform into a stronger form—Mumm-Ra, the Ever-Living—by reciting the incantation "Ancient Spirits of Evil, transform this decayed form... to Mumm-Ra, the Ever-Living!", and has the power of shapeshifting. He can not truly be killed, as, even if his body is destroyed, he will be restored.