Hammerface

 Hammerface, A.K.A. Experiment 033, is an illegal genetic experiment created by Jumba Jookiba. He is designed to hammer nails around Jumba's house. He was captured by Gantu, but was rescued in "Snafu." His one true place is with the local charities to help make houses for the poor by hammering its nails. Hammerface is voiced by Jeff Bennett.

Bio
Experiment 033 was the 33rd genetic experiment created by Jumba with Hämsterviel's funding. He was designed to drive nails around Jumba's house.

033 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.

Lilo & Stitch: The Series
033's pod eventually made its way to a junk shop, where it, along with 609, 617 and 544, was stolen by Gantu, activated, and named Hammerface in "Dupe."

Plasmoid, Heat, Thresher and Hammerface were then led by Gantu in an attack on the Pelekais' house, where Hammerface and the other three experiments were able to easily defeat and capture Stitch and his replicas.

The five returned to Gantu's ship for a victory feast, but were interrupted by Lilo, Pleakley and Dupe. Gantu used Dupe to clone Hammerface into a hundred replicas, but as Hammerface's power was thus divided between them, they were complete weaklings.

It is presumed that Hämsterviel was somehow able to re-merge the weakling Hammerfaces into one.

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

In "The Asteroid," Hammerface was one of the six experiments who Stitch convinced to come with him and Lilo to save Earth from an approaching asteroid. During the journey, Sparky pranked Hammerface by electrocuting him, angering the latter.

Leroy & Stitch
The first 624 experiments, including Hammerface, 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.

Hammerface participated in the following battle between the experiments and the Leroy clones.

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.

Stitch! anime
Hammerface makes an appearance in Season 2 of the Stitch! anime along with Spike, Woody, Link, and Babyfier.

Trivia

 * Hammerface is one of the ten known experiments named by someone other than Lilo, the other nine being Gigi, Yaarp, Elastico, Thresher, Heat, Plasmoid, Morpholomew, Shrink, and Leroy.
 * Hammerface is Experiment 033. However, in Stitch! The Movie, he is called 124, most likely due to Jumba's untidy database.
 * In "The Asteroid," Pleakley referred to Hammerface as "Hammerhead." Presumably because his head is indeed shaped like a hammer.
 * Hammerface's pod color is white.
 * Hammerface is described by the experiment computer screen as, "Experiment 033, Primary function: Nail driving."