(coexisting on another dimensional plane)
Lieutenant Hikaru Sulu was the security chief, helmsman and second officer aboard the Terran Empire starship ISS Enterprise, under Captain James T. Kirk. This Sulu had a scar on his face from unknown reasons and had an infatuation with the ship's communications officer, Lieutenant Uhura.
In 2267, four crewmembers of the USS Enterprise crossed over into the mirror universe during a transporter malfunction while attempting to transport through an ion storm. In their attempt to escape, it was the mission of Lieutenant Uhura to distract Sulu from his security display, which she was successful in manipulating.
A fight later broke out in sickbay as the four crewmen approached the final stage of their escape. Sulu arrived with a security squad and had previously warned Spock that if the Vulcan was not able to command the ship, he would take command. Sulu would, in turn, be defeated when the "captain's woman", Marlena Moreau, utilized the Tantalus field against Sulu's posse, allowing the four members of the USS Enterprise to return back to their universe. (TOS: "Mirror, Mirror")
Like his prime reality counterpart, Sulu was portrayed by George Takei.
The mirror Sulu appeared as captain of the mirror universe Excelsior in the video game Star Trek: Shattered Universe. Due to a temporal distortion, the prime universe and mirror universe Excelsior crews switched places, with both sides making their way across the galaxy to another temporal rift in order to return to their own universes.