Now that we've gotten our first good look at Ultron in the second Avengers movie, it's time to step back and see what makes him one of their most dangerous — and most feared — foes. Here are six adventures with the homicidal robot where the Avengers needed some avenging themselves.
1) "We Stand at Armageddon," Avengers #67
The Avengers are confused when their android teammate the Vision steals a cylinder of a recently discovered element named adamantium, and they're aghast when they realize he's used the indestructible material to rebuild his evil creator Ultron (thanks to Ultron briefly reasserting his control over his former creation). Ultron 6, as he's known, kicks the collective asses of Thor, Iron Man, Black Panther, Goliath, Yellowjacket, the Wasp, and even the Vision, who quickly regains his independence. Now indestructible and his main foes defeated, Ultron-6 casually saunters out of Avengers Mansion and gets to work building a nuclear bomb to destroy New York City.
2) "He'll Rule the World," Fantastic Four #150
Ultron-7 crashes the wedding of Quicksilver and his Inhuman bride Crystal with help from Maximus, the evil brother of the Inhuman king Black Bolt. Despite the fact that the Avengers, the Fantastic Four and a large posse of Inhumans are in attendance at the wedding, Ultron fights them all to a stand-still and unleashes a weapon that will destroy the minds of every single hero there. Only a fluke keeps Ultron from taking out three of Marvel's greatest teams of heroes at once — the device wakes up young Franklin Richards from his dad-induced coma (long story), and he uses his reality-warping powers to destroy the bad robot menacing his family.
3) "The Bride of Ultron!" Avengers #162
Honestly, Ultron trying to make himself a companion isn't a particularly nefarious plan, nor is it that dangerous. But in Ultron's quest for a little bit of robo-nookie to call his own, he brainwash Hank Pym and has him attack his fellow Avengers with ants — telling him that they're robot duplicates trying to kill the Wasp, when in fact Ultron wants the Wasp to use her brain patterns to make his wife. The Avengers defeat Ant-Man of course, but that's when Ultron walks into Avengers Mansion and basically starts kicking ass. He takes out Captain America, the Vision, the Scarlet Witch and the Beast (during one of his Avengers stints), and takes Ant-Man and the Wasp at his leisure, eventually tricking Pym into transferring the Wasp's lifeforce into his bride's new robotic body. Of course, the bride, likely with help from the Wasp's good-hearted consciousness, foils Ultron's plans by summoning the remaining Avengers, who threaten to destroy his wife if he doesn't release Ant-Man and the Wasp immediately.
4) Ultron Unlimited, Avengers #19-22
Written by Kurt Busiek with art by George Perez, this '90s saga is generally considered the best Ultron storyline, in which the evil robot not only kicks the Avengers' collective asses multiple times, but also murders the inhabitants of an entire country (Slorenia, if you're wondering). Ultron-17 also unleashes an entire army of Ultron robots to attack the Avengers, and is able to capture the Vision, the Scarlet Witch, the Wasp, Wonder Man, and even his creator Hank Pym currently using his Giant-Man moniker. As usual, the Avengers are losing until someone pops up with a deus ex machina, this time in the form of vibranium, which is Ultron-17's weakness. Still, though — robot dude murdered a whole country. You have to call that a loss for the Avengers no matter what.
5) The Ultron Initiative, Mighty Avengers #1-6
When Ms. Marvel was asked to lead her own team of Avengers in 2007, post-Civil War, she probably didn't expect Ultron to 1) show up looking like a naked, robotic version of The Wasp, or 2) hitch out of Iron Man's armor, essentially killing Tony Stark (that's what he gets for merging his technology with his biology). Now, at the time the Mighty Avengers included both the Sentry and Ares, so this new female Ultron managed to fight the Marvel equivalent of Wonder Woman and Superman, along with the literal god of war, to a standstill, all while crashing one of SHIELD's helicarriers, taking over two satellites with the power to control the weather, murdering the Sentry's wife, reprogramming Iron Man's old armors to fight the Avengers, and firing a nuclear missile. Not a bad day's work for any supervillain.
6) Age of Ultron
This 10-issue miniseries is the definitive example of Ultron kicking the Avengers' asses, because it begins with Ultron already having done so. Ultron has taken over the world, and has his own sentinels looking for the heroes who have not yet fallen who are in hiding. Ultron's rule is so absolute that the remaining heroes must use a time machine to fight Ultron before he arrives (they have to go to the future, as this Ultron traveled back in time), while Wolverine decides to head into the past to murder Hank Pym before he can ever create Ultron. The plethora of time travel borders on the absurd, and causes more than a few tears in the space-time continuum, but Ultron is only defeated when future Hank Pym sends some necessary equations to present-day Pym just before Ultron arrives.