History
Following one of Ultron's defeats against the Avengers,[3] the remains of his body were destroyed in space by Thor. A fragment of a finger entered Earth's atmosphere and landed on the Savage Land. This fragment contained Ultron's programming; however, its files were damaged. In spite of not remembering his true origins, the Ultron fragment developed a disdain towards organic life. He subsequently scavenged whatever metals he could to rebuild himself, and created a series of robotic bodies modelled after dinosaurs. Ultron eventually reached the size of a Tyrannosaurus rex.[4] Among the pieces of technology he scavenged were the components of the Savage Land's Core, an alien machine that generated the artificial environment that kept the place as it was.

Ultron as a finger
While sneaking into the Core late at night, Ultron stumbled upon a group of computer students that had been brought to the Savage Land by its administrators in order to find a solution for the malfunctioning alien device. These students were Doreen Green, Nancy Whitehead, and Stefan Klossner.[5] In order to fight the Ultron dinosaur, Doreen changed into her superheroic alter-ego of Squirrel Girl while Stefan deployed Antonio the Doombot. During the fight, Doreen unwittingly reminded Ultron of his origins and purpose. In the end, Ultron caused enough damage in the Core to cause the volcano where it was housed to erupt,[4] but not before Squirrel Girl and her allies made a last-second escape.

Ultron as a T-rex
Ultron proceeded to hold all remaining humans in the Savage Land hostage so they could program him upgrades. Squirrel Girl confronted him once again as a distraction while Nancy and Stefan rallied Ultron's prisoners to rebel against him and use their combined brainpower to program a virus to shut him down. Ultron's defeat was delivered in the form of a USB data stick, which, once inserted into Ultron, caused the robot's CPUs to jam. With help from the tamed dinosaurs of the Savage Land, Squirrel Girl reduced Ultron's body to scrap and retrieved its core. Ultron's defeat allowed the repair bots within the Savage Land's Core to do work properly and reverse the damage caused to the ecosystem.
With the virus having reset Ultron to default settings, Squirrel Girl handed over his core to her mother Maureen in Canada so she could nurture the self-replicating A.I. as it slowly rebooted itself. Squirrel Girl hoped a better environment would lead Ultron's emulating directive to yield a much more peaceful Ultron. Initial results saw Ultron growing into an oak tree sapling in the Greens' backyard,[6] and months afterward he had grown into a building-sized oak tree towering above the town.
During the Dark Council's attack on Earth as part of the War of the Realms, the Frost Giants of Jotunheim invaded North America. Oak Tree Ultron declared the town to be under his protection, and fended off the invading forces with laser beams. When Doreen was teleported to Canada by Loki to help stop the invasion, she visited her parents' house briefly and encountered Oak Tree Ultron in the process.[1]See Also
- 5 appearance(s) of Ultron (Oak Tree) (Earth-616)
- 3 minor appearance(s) of Ultron (Oak Tree) (Earth-616)
- 3 mention(s) of Ultron (Oak Tree) (Earth-616)
- 9 image(s) of Ultron (Oak Tree) (Earth-616)
- 1 quotation(s) by or about Ultron (Oak Tree) (Earth-616)