Ermac

Ermac is a fusion of the souls of dead Outworld warriors and a hero from the Mortal Kombat series of fighting games.

Creation
Ermac was created by Shao Kahn by fusing together the souls of fallen warriors from Outworld. At some point, he met Shujinko while in the Netherrealm (most likely on a mission from Shao Kahn there) and was attacked by Ashrah, who believed that he was a demon.

Turn to Good
Ermac fought for Shao Kahn during his invasion of Earthrealm, but after his master's defeat and loss of power, he began wandering Outworld, lost without any instruction. During the rise of the Deadly Alliance, Ermac was found by Kenshi, the blind swordsman who freed him from the control of Shao Kahn and in gratitude, he taught Kenshi how to use telekinesis. Now free to chose his own path, Ermac decided to become a force for good to make up for the evils of his past.

Fighting on the Side of Light
Soon after this decision, Ermac came across the soul of Liu Kang, who understood his suffering. The monk needed a new ally and someone to assist him in freeing Jax Briggs, Johnny Cage, Kitana, Sonya Blade, and Kung Lao from the control of Onaga. Ermac was eager to do so, since this was an excellent opportunity to make up for some of his past evils. After finding them, the soul fusion battled Liu Kang's enslaved friends while Kang freed them and eventually they succeeded in freeing them all.

In his Mortal Kombat Armageddon ending, after defeating Blaze, Ermac was split into the many warrior souls that comprised him, each with a physical body. But each was connected psychically so in essence, Ermac had been transformed from one warrior into an army.

Powers
Ermac is a master warrior thanks to being a fusion of many warrior souls and fights with powers related to the soul. His most used power is his telekinesis and he also can manipulate soul energy to levitate and fire energy blasts. However Ermac does have one weakness, the Netherrealm, which weakens him the longer he is there since he is a being of magic. It also weakens the bonds that hold the souls composing him together, threatening his existence. As his alternate weapon fighting style, Ermac wields an axe.

Trivia

 * Ermac was actually inspired by a rumor amongst MK fans about a secret red clad ninja character in the original Mortal Kombat that would appear whenever a player overused Scorpion.
 * In Ultimate Mortal Kombat 3, human Smoke had one of his fatalities.
 * Since he is a being comprised of many entities, Ermac refers to himself in plural (i.e. saying "we" instead of "I" and "our" instead of "my").
 * In Mortal Kombat Shaolin Monks, a Game Over message says to "Ask Ermac For Help", which is meant to act as a hint that he exists as a secret boss at the Warrior Shrine. This also parodies the rumors that he was in the first Mortal Kombat.
 * When he is knocked off the Sky Temple in Mortal Kombat Deception and Unchained, Ermac briefly shouts "Suck it!"
 * He and Ashrah are the only "good" characters to ever be enemies.
 * Ermac is seen in the intro to Mortal Kombat Armageddon, first using a clothesline on Rain. After the fighters began charging up the pyramid, Shang Tsung in the form of Ermac and Nightwolf punched at Sheeva, but she held them off and almost choked them until Kenshi stabbed her in the chest. After Quan Chi defeated Kenshi, Ermac used his telekinetic powers to throw the sorcerer off the pyramid and then changed back into Shang Tsung as he stomped on Kenshi's chest.