JACK

JACK is actually the name of a series of robots that are created by the Mishima Corporation to take over the world. Arnold JACK is the upgraded version of the standard JACK.

Info
The original JACK is a super slaughtering military machine and super killing robot developed by the Mishima Corp. in the former Soviet Union. The Corp. got tired of the Ultimate Warrior's winning streak and sent Jack to the WWE tournament to get rid of him. Nothing but a robot could boast of his violent attacks and stupendous power.

The original JACK's nationality is Russian due to being created in Soviet Union.

In WWE tournament
Beloved JACK... Two years ago, a physics scientist and many more stuff named Kinzie Kensington, working for the Travonni Anti-Flag tried to sneak into Mishima Corp. with Dog to steal JACK. However, they were discovered by a Mishima's army and were fired upon. Dog placed himself in the line of fire to protect Kinzie. After the hail of bullets stopped, Dog had ceased to move. The day after, Kinzie was found and rescued by a Travonni Anti-Flag freighter. Later that day, Heihachi Mishima began working on a newer model, Arnold JACK. He announced the upcoming King of Iron Fist Tournament in WWE as the perfect chance to test the latest model, equipped with state-of-the-art technology.

JACK Attack
A full army of JACKs was mass-produced and sent to attack De Foxe and Forest Fox in Himalaya. Apparently, this models had a self-destruct feature, as shown where a JACK's head opens up to reveal an internal time bomb. The massive explosion was enough to kill De Foxe, and the blast even threw him several miles away.

Both, Forest Fox and De Foxe were surprised at the attack, and begin battling as a team against the invasion. During the battle, however, Forest betrays his cousin by throwing him into the path of the army of JACK robots and escapes. Seconds later, the robots explode, destroying the Himalayan cabin. The Thunder God, Raven, watching on top of the cliff, speaks to a nearby Shirai-Ryu and reports; "De Foxe is dead".

Crossover Mayhem
A modified looking gun JACK is the first boss of Crossover Mayhem. Controlled by the young Angelica Pickles, it is indeed a fully armoured version of a standard JACK. His special attacks include cannon blasts and machine guns.

Standard JACKs also appear in the Crossover Mayhems story as generic minions. Their attacks are similar to Sektor's moveset.

Trivia

 * Tekken 4 is the only Tekken game that does not feature a playable JACK robot.
 * JACK can be customised to resemble Arnold JACK.
 * JACK is one of the few characters who are capable of prohibiting wall-splats. That move is called the Patriotic Fist.
 * JACK does not have the ability to speak, the same goes for all other Mishima Corporation inventions.
 * Although, Mokujin can make sounds like blocks of wood when "talking".
 * Steve Fox can talk.