Tank (Lilo & Stitch)

 Tank, A.K.A. Experiment 586, is an illegal genetic experiment created by Jumba Jookiba. He is designed to eat metal and grow larger with each meal. He was captured by Gantu, but was rescued in "Snafu." His one true place is eating scrap metal at the junkyard. Tank is voiced by Frank Welker.

Bio
Experiment 586 was the 586th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to eat metal and grow exponentionally bigger with any metal he ate.

586 and the other first 624 experiments were deactivated and smuggled to Earth by Jumba during his mission to capture Experiment 626.

All of the experiment pods were released and scattered across the island of Kauai, with 586's pod landing in a car's vent.

Lilo & Stitch: The Series
When the car was being washed, 586's pod got wet, activating him. 586, named Tank, then ate the automobile and proceeded to eat metal throughout town until he grew to a large enough size to go on a rampage.

Gantu had been informed about the experiment and realized he wouldn't be able to catch it in a containment orb, due to how large it had grown. He then decided to take the hovercraft and find another way to capture Tank.

Meanwhile, Lilo was having fun at the Kauai Medieval Festival with the hula girls (who ditched Mertle due to her desire to play dolls all the time), but neglected Stitch when he told her that an experiment was on the loose. Later, Stitch teamed up with a lonely Mertle in hopes of stopping Tank.

However, due to his enormous size, Tank proved impossible for Stitch to conquer. Tank's rampage continued to spread, where, after an attack on Stitch, he was captured by Gantu using a tractor beam. Regardless, Lilo had requested Gantu to get Tank away from Stitch, since the latter appeared to be outmatched.

Additionally, Mertle broke off her temporary friendship with Stitch when the hula girls took her back, while Lilo and Stitch made up.

Tank reappeared in "Snafu," and was freed along with Gantu's other captive experiments by Lilo, Stitch, and several other experiments in a rescue mission.

Leroy & Stitch
The first 624 experiments, including Tank, were round up by Leroy and taken to a stadium to be destroyed. However, Lilo, Stitch, Jumba, Pleakley, Reuben and Gantu arrived before the experiments could be destroyed.

Tank participated in the following battle between the experiments and the Leroy clones by eating attacking Leroys.

However, the Leroys soon gained the upper hand in the battle, but were defeated when Lilo, Stitch, Reuben and several other experiments performed the song Aloha `Oe, which caused the Leroy army to shut down due to the original Leroy's failsafe.

Trivia

 * Tank has shrunk from a massive size back to his normal size between "Tank" and "Snafu," suggesting that he returns to his normal size after a while without eating any metal.
 * Tank's pod color is blue.
 * Tank is described by the experiment computer screen that says "Experiment 586 Primary function: Metal consumption. The experiment becomes bigger with everything it eats."