Name: Ermac
Origin: Unknown (Presumably the Outworld)
Race: Telekinetic Entity
Playable Debut: Ultimate Mortal Kombat 3 (Home)
Unplayable Debut: Ultimate Mortal Kombat 3 (Arcade; playable with code)
Story: Ermac, the enigmatic ninja, has been around since before the first tournament, but never surfaced until the invasion. Although the enormous cloud of mystery which hovered around him was never fully revealed, it has been rumoured that the many Outworld warriors who died in battle had souls which never passed over into higher existence.
Instead, they merged into one of the most powerful entities ever to exist on any realm: Ermac. Ermac was a telekinetic ninja who appeared during the invasion. As a collection of Outworld souls, he was loyal to Kahn.
Ermac fought like a storm through the Human forces, but even he could not counter their power. Although he never himself received a scratch from battle, he did witness the disproportion of Kahn. Realizing the danger he was in, Ermac fled through the corrupted portal, the moment before it collapsed.
Ermac never arrived on the other side.

(Editor's Note: There's a faint, somewhat unreliable rumour floating around the web stating that Ermac is the second hidden character of MKGold. If this is true, the Temple will report it as soon as it is confirmed.)