On paper, a large bearded man invading millions of homes on the same night every year sounds terrifying. We accept it as kids because it's Santa Claus, and also we are dumb gullible post-fetuses, but when adulthood rolls around you realize that the man eating your milk and cookies has a rap sheet of misdemeanors a mile long. So when the Avengers Christmas Party is interrupted by some dude in a red suit with the dead-eyed stare of the Burger King mascot, it sorta freaks everyone out.
It wouldn't be much of a comic if Creepy Santa turned out to be Morph playing a Christmas prank on everyone, so yeah, it's a dastardly Terminator-like robot with a neural disruptor. Santa-bot also has some sort of Naughty/Nice protocols running, but it's hard to tell what the criteria is for deciding who belongs on which list. Iron Man could be on the naughty list for anything from arms dealing to operating an exosuit while under the influence, but what has Captain America ever done to warrant a lump of coal? Dude's more squeaky-clean than a mouse being run over by a street cleaner. It makes a bit more sense when Wolverine reveals the identity of the Kringledopper.
Ultron. As in, the villain of the Avengers movie sequel Age of Ultron. In most cases this reveal would mark the beginning of a months-long event spanning two dozen different comics, but the situation was resolved pretty quickly when the good guys figured out Santron was created by a sad human woman who just wanted Santa Claus to be real. She didn't get her wish, but at the very least I'm sure the Avengers can get James Spader to do her voicemail message or something.
One of the most powerful artifacts in the Marvel universe is known as The Infinity Gauntlet, which affords its user control over the very fabric of reality. Anyone who wields it basically has access to God Mode, super Matrix Neo powers and unlimited breadsticks at Olive Garden all at once. So it's baffling that The Avengers thought it was a good idea to hand it over to Santa Claus when his reindeer were knocked out of commision by a bad case of "being aliens." Using the Infinity Gauntlet to dole out presents to humans on one piddly planet is incredible overkill, like swatting a fly with The Moon.
But there's something you should know about St. Nick in the Marvel Comics Universe. See, it's been strongly implied on more than one occasion that not only does he exist, but Santa is in fact a mutant; back in 1991's Christmas Special, he was detected as "the most powerful mutant ever registered." In that same issue, he turned the Brotherhood of Mutants into harmless toys, teleported the X-Men away and wiped everyone's memories. Santa Claus is not fucking around. It's dangerous to grant even a mortal human the power of the cosmos, but to haphazardly fork it over to someone who's essentially a demigod is downright wreckless.
Thank god for Namor's throwing arm.
And so trillions of lives were saved, existence itself was prevented from collapsing with a single snowball hucked by Marvel's angsty version of Aquaman. You have to give Santa credit, he plays the "temporary insanity" card quickly and convincingly. But there's still the matter of the errant reindeer, which Iron Man settles with a solution that probably should have came somewhere before "Give Omega-level mutant the universe-ending Power Glove."
Ha ha, get it kids? It's funny because the Iron Reindeer were programmed to struggle with alcoholism.