Gun Jack

Jack is a series of androids created by the Mishima Zaibatsu and G Corporation for different purposes:

Jack is the original model, and was created by the Mishima Zaibatsu in order to counter a coup from Kazuya Mishima in the King of Iron Fist Tournament.

Prototype Jack is a prototype of Jack was created to combat both Jack and Jack-2. It was destroyed by Jack-2 in the second tournament. This is also the only Jack to fight in more than one tournament.

Jack-2 is the upgrade of Jack, also created by the Mishima Zaibatsu. One of these models, while on a battlefront, witnesses a young girl named Jane lose her mother, and takes it upon himself to look after her until he is destroyed by Dr. Abel.

Gun Jack is a more advanced prototype of the android, created by Jane in an attempt to revive her friend, Jack-2. While she is successful in implanting Jack-2's memories inside him, he is destroyed by gunfire by the Tekken Forces after he and Jane attempt to break into the Mishima Zaibatsu labs.

Jack-4 is an upgrade of Gun Jack, created by G Corporation. While these never participated in any tournament, they were sent by G Corporation to kill Kazuya Mishima after they no longer needed him, and the subsequent battle in Hon-Maru almost resulted in the death of Heihachi Mishima. These specific models have a self-destruct device embedded in them, indicated when the face peels away to reveal a countdown.

Jack-5 is an upgrade of Jack-4, created by Jane to participate in the King of Iron Fist Tournament 5. His fate is currently unknown.

Jack-6 is an upgrade of Jack-5, created by G Corporation with the mission of destroying the Mishima Zaibatsu in the King of Iron Fist Tournament 6.

GameDaily placed Jack 24th on their "Top 25 Video Game Robots" list, stating "While not the most popular character in the Tekken series, Jack punched its way to become a worthy opponent."