Ultron

An evil, sentient robot created by Dr. Henry Pym. Somewhere along the way, the robot became evil, and is a recurring bad guy intent on destroying Dr. Pym and the Avengers.

He has been defeated a number of times, only to keep reappearing. One of the more recent forms he has adopted is a robotic body made out of the indestructable metal Adamantium, so he's now really hard to stop.

He made the being now known as the Vision, who ended up being a superhero.

He lives in the Marvel Comics universe.

• Ultron-1 first appeared in Avengers #54.
• Ultron-5 programmed the Vision.
• Ultron-6 was the first adamantium Ultron. He is also known (in a very Japanese turn of phrase) as "Ultimate Ultron".
• At one point he operated under the alias Crimson Cowl, and as such led the Masters of Evil.
• His Achilles heel is the magical power wielded by the Scarlet Witch.
• In an effort to build himself a companion he attempted to upload the mind of Dr. Pym's ex-wife Janet Van Dyne into a robot body he dubbed Jocasta. (Get it? Because she was married to his father? Who says comics aren't intellectual?) He didn't count on the Wasp's morality carrying over as well, though -- Jocasta turned against her creator, and though she still loves the big evil lug, she now fights on the side of the Avengers.

It is difficult to chart the appearances of Ultron. Some stories have him with a numerical designator (model number), and some do not.

The Ultron that appeared in Secret Wars had no designation save his ordinary nome de plume. (Within that story Ultron went through at least two different evolutionary structural design changes, one from being rebuilt by Dr. Doom and the other from being recreated out of thin air by Klaw. It's not clear whether or not Ultron considers these to be iterations of himself.

Ultron has appeared in at least one dream sequence comic, where he battled the Fantastic Four as Ultron-13. Seemingly, the writers forgot that this was a Dallas type story that never happened, because the next time Ulty appeared, (in West Coast Avengers he was calling himself Ultron-14. *tsk* Doesn't everybody know this crap?