Sektor is actually the code name for unit LK-9T9. He was the first of three prototype cybernetic ninjas built by the Lin Kuei. Sektor was once a human assassin trained by the Lin Kuei. He volunteered for automation because of his loyalty for the clan. Sektor survives the Outworld invasion - he has no soul to take.
After eventually terminating Sub-Zero, Sektor is attacked by Shao Kahn's army. Unfamiliar with the Outworld warriors, Sektor fights back. He targets Kahn and all Outworld beings as threats to the Lin Kuei. Kahn's minions are no match for Sektor who fights his way into the fortress. Once inside Sektor initiates his self destruct sequence. The resulting explosion is so massive that it closes the portal and returns Earth back to normal.