Baterra

It is a baterra that was found, abandoned and glitched, on a far away world by Makuta Caiaphus himself. He has employed it in his service for a time. Books LLC still sucked then.

However, it seems the Makuta no longer had any use for the shapeshifting droid, as he abandoned it on the Mata Nui II, with the Keruvim trapped inside of its body (Caiaphus had "reprogrammed" it, placing the artifact in his body, ala Cad Bane). When all hope seemed lost for our insane baterra, Klak saved it by removing the artifact. The baterra was later thrown into a portal. Here, it went through a great deal of film references and insanity, and found its way on some random ship.

Somehow, it ended up close to Klak, and merged with something shiny. That turned out to be the Keruvim. But it was removed.

After plenty of adventures being at Klak's side, the Baterra ended up joining the Rebel Alliance, and helped D-Klak fight off the Pirates in the Battle of Liquid Metallicon.

Afterwards, he was kidnapped by Angonce and his scientists, who experimented on him, turning him into a weapon to purge all remaining war veterans.

This resulted in transforming him into a mindless murdering monster, as demonstrated in his brutal murder of a Uterio War combatant, and attempted murder of Klak and many of the plague victims of RacKoon City. However, the Baterra was shut down, and was researched by Malchiorian scientists in an attempt to reverse the effects of Angonce's experimentation.

He escaped the research facility and united with Rahn and Shadow Blade, agreeing to help them. You can already guess what happened to the Malchiorian scientists attempting to break Angonce's experimentation. Trust us, it's not pretty.

It is unknown what happened to the Baterra as of Ragnarok.

Abilities and traits
The baterra, being glitched, was completely insane. It randomly switches targets, and can only have one at a time. Also, it shapeshifts into things that are quite....strange.

However, this creature is an extreme survivalist, able to live through almost any condition. In addition, the baterra's insanity makes it exceptionally deadly, and dangerous.

As of the end of the Uterio War, the Baterra is no longer the insane, trigger happy robot we all know and love. Instead, he is a mostly silent, shapeshifting, murdering machine. It's what he was built for, after all.