Reiko has served both Shinnok and Shao Kahn. After Shinnok's death, Reiko disappeared and later reappeared as the General of Shao Khan's forces.
He is often mistaken for Shao Kahn, due to the similarities in their attire. He has been seen to put on Shao Kahn's helmet and express his will to replace the emperor someday. He also states in-game that he will one day rule Outworld himself.
Reiko has an unknown disliking of Quan Chi. He quickly allies with Taven - another character who wants Quan Chi dead. Later on Reiko tries to get Taven to join Shao Kahn's army, but Taven denies since his primary goal is to find and kill Quan Chi. That is a good opportunity for Reiko to see Quan Chi finally defeated, but unfortunately he had been ordered by Shao Kahn to protect the emperor's allies. Taven defeats Reiko, who limps away but is content in the ironic twist that his failure to beat Taven would likely result in Quan Chi's own demise.
Reiko has also been a member of the Brotherhood of Shadow where he worked formerly with Noob Saibot and Tanya under the command of Quan Chi.
Mortal Kombat 4
Reiko steps through a portal, which leads him to Shao Kahn's throne room and Shao Kahn's helmet eventually lowers on to Reiko's head.
Mortal Kombat Armageddon
Reiko receives godlike power and his hunger for domination returns. More powerful than even Shao Kahn, he defeated the emperor and claimed his helmet. He then turns into a furious warlord.
- Thrust Kick: Reiko delivers a might kick to opponent's torso which causes it to fly right straight off as the arms and head are left spinning in midair whilst the legs crumble to the ground. The arms land on the ground moments later (MK4, MKG)
- Shuriken Barrage: Reiko throws a deadly multitude of shurikens at the opponent, covering the entire body before throwing the last one in to the head, causing the opponent to fall in a puddle of blood (MK4, MKG)
- Reiko has been subject to controversy involving him and Shao Khan. When Mortal Kombat 4 was released on consoles his ending was altered from just going through a portal to showing Reiko go through the portal and then having Shao Khan's helmet placed on his head. This lead people to speculate that he was in fact Shao Khan himself. A fact later put to rest by Ed Boon as false.
- Reiko makes an appearance in the Pit II Stage of Mortal Kombat (2011) he is seen fighting on the parallel bridge against either Daegon, Frost, Sareena, or Kenshi.
- Reiko is also briefly mentioned by Shang Tsung during the Mortal Kombat (2011) Story Mode.
- Reiko's eyes are completely white in every appearance he's made except for in Mortal Kombat 4 where his eyes are blue.
- The Black markings over his eyes are tattoos.
- Reiko in Mortal Kombat 4 was originally intended to be Noob Saibot, but due to issues with Noob Saibot and the complaints of there being too many Ninja characters they modified noob by changing his head, adding gauntlets, giving him a skin tone, changing the suit color from Black to Maroon and ultimately having a whole new character. If you unlock Noob in the console versions of the Mortal Kombat 4 you can see the aesthetic similarities.