Jack is the first robot in the Jack-bot series. It is unknown how it was destroyed. Jack was sent to get rid of Kazuya. Jack, unlike Jack-2, Gun Jack and Prototype Jack, did not appear in Tekken Tag Tournament making him the only Jack robot (before Jack-5) not to appear in more than one game.
Jack-2 is the second robot in the Jack series. He is an upgrade of the original Jack robot and was sent out to enter The King of Iron Fist Tournament 2 to save his creator and friend, Jane from the evil Kazuya Mishima. In his ending, Jane and Jack-2 are playing on an island together. Suddenly, Jack-2 gets shot by a laser from a satellite up in space that Doctor Abel uses to destroy Jack-2.