Making his official debut in Ultimate Mortal Kombat 3, Ermac has been a controversial and mysterious character in the Mortal Kombat series whose existence was rumored since its inception. It is now clear that Ermac is an amalgam of many souls destroyed in Outworld's wars who came to be controlled by Shao Kahn and his shadow priests. Because of this, he commonly refers to himself as "we", "us", and "our" instead of "I", "me", and "my". Due to the sheer concentration of souls within Ermac, he possesses the gift of telekinesis and can travel to different realms. However, the depths of Netherealm drain his powers and souls. He is weakened dramatically while there.

He made his return in Mortal Kombat: Deception, where he was freed from Shao Kahn's grip by the blind swordsman Kenshi. He decided to become a force of good partly in guilt of his past evils. To prove this, he decides to help Liu Kang free the souls of his friends from control of Onaga.