Jack 5
The Jacks are robotic fighting machines that have taken part in the various Tekken tournaments. Never has one model competed in more than one competition, or for the same purpose; more often, an upgraded model takes the place of the previous one. The Jack series has been through 6 different incarnations:
Jack
Jack was the original version created by the former Soviet Union. He was sent into the first tournament to help return Russia into a communist state.
Jack-2
Jack-2 is an upgraded model of Jack with an artificial intelligence chip built in to allow learning. After rescuing an-eight-year-old girl named Jane from a battlefield, Jack-2 felt obligated to become more human to care for the little girl. Therefore, he sought out Kazuya, who he hoped could make him more human. Unfortunately, Jack-2 was destroyed by Dr. Abel via satellite while a horrified Jane watched.
Prototype Jack
A prototype of Jack was created to combat Jack and Jack-2. It was seemingly destroyed by Jack-2 in the second tournament.
Gun Jack
Twenty years later, Jane, haunted by memories of Jack-2's fate, works on a way to restore Jack-2. She learns that most of the technology responsible for Jack-2's A.I. was created by Mishima Heavy Industries, a subsidiary of the Mishima Zaibatsu. She also finds the ground work for something called "Project Gun Jack"--an upgraded Jack with a pivot gun. Jane snuck into Mishima Heavy Industries and secretly installed a hidden program. At the third tournament's conclusion, Heihachi's Tekken Force attacked Jane. She was rescued by Gun Jack, who was destroyed by the onslaught of gunfire. Jane escaped with the help of G-Corporation. Dr. Abel too, tried to destroy this version of Jack, but ultimately failed. This sequence of events is only viewed in Gun Jack's alternate ending in Tekken 3.
Jack-4
Never entered in the tournament, but was mass-produced by G-Corporation thanks to Jane's research. These versions of Jack attacked Kazuya and Heihachi at Hon Maru and self-destructed, almost killing Heihachi.
Jack-5
The latest version of Jack. Jane created him as an upgrade of Jack-4 and plans to use the tournament as a means of testing Jack-5.
Information for both of these characters came from: http://en.wikipedia.org/wiki/Main_Page
