As part of a plan to take over Ultron's reign, Doctor Doom assembled a team of Avengers from different points in time, and had two of them, Vision and Iron Man, assault the Avengers Tower, the location from where all of Ultron's drone factories were controlled.
Vision and Iron Man successfully accomplished their mission, believing to have destroyed the power source of the factories. However, Doom had lied to them, and what they had destroyed was actually the security systems, allowing Doom to hack into the factories and gain control of Ultron's army, retrofitting the drones to his own image.
Following Ultron's defeat, Doctor Doom used the newly-aquired army to hunt down the time-displaced Avengers, who had escaped before Doom could send them back to their time periods. After finding themselves surrounded by a never-ending army of sentinels, the Avengers took the fight to Doom, and convinced him to free the Earth.
The untimely death of Hank Pym's wife the Wasp, Pym went on to create a more brutal version of Ultron, which was to replace the Avengers. Ultron's sentience began to constantly evolve, he started the eradication of the human race by taking out such threats as the Avengers and the Defenders while he left Pym alive to watch him suffer. Ultron and his army of Ultron Sentinels then moved to Kola, Russia so he could bore himself into the planet's core itself to create the ultimate version of himself, Ultron-1320. Pym attempted to stop him, but he was captured and converted into Ultron-1321.
Ultron later learned to travel into different realities using tears created by the multiversal chaos brought on by Wolverine's time traveling. He invaded several realities using an army of Ultron Sentinels. With the assistance of Hank Pym of Earth-14622, the Avengers Infinity traveled to Ultron's base in Kola, Russia and destroyed his power source thus ending Ultron's threat.
- 48 appearances of Ultron Sentinel
- 19 minor appearances of Ultron Sentinel
- 8 mentions of Ultron Sentinel
- 89 images of Ultron Sentinel
- Gallery of Ultron Sentinel