'Avengers: Age of Ultron': Explaining That Crazy Mid-Credit Scene

— -- Wait, what just happened?!

Warning: SPOILERS AHEAD!

Many "Avengers" fans might be a bit confused -- or very excited -- when they watch that last, mid-credit, scene from "Age of Ultron" and see Thanos grabbing what looks to be a metal glove.

Possibly the most powerful villain in all the Marvel Universe grabs a metal glove, called the Infinity Gauntlet -- and puts it on saying he'll have to do it himself.

Do what himself?

Well, the Infinity Gauntlet is one of the most powerful weapons in all the galaxy ... if it has the Infinity Gems that go into the front of the glove. If you saw "Guardians of the Galaxy," you know that Thanos wanted his adopted daughter Gamora, played by Zoe Saldana, to steal one of these gems and you also saw just how powerful just one gem can be -- killing average people if they even touch it. Imagine what six together can do.

Infinity Gems from the movies in the Marvel Universe can be found in Loki's Sceptre, which he lost in the first "Avengers" and is now ... (you'll see in the movie), and the orb, which is under the care of Nova Prime, played by Glenn Close.

What Thanos wants to do is unite the gems and then he'll have unlimited power. ABC News spoke to Marvel Executive Editor and Senior VP Tom Brevoort to talk about the storylines for Infinity Wars last year, as they pertain to the comics. There will obviously be key differences in the movies, but here's the gist.

"Inifnity War really was part of a trilogy. We did three stories -- Infinity Gauntlet, Infinity War and Infinity Crusade. It was this big, sprawling, epic Thanos story. How much the films will pull remains to be seen. ... The crux of this Infinity Trilogy, Thanos as a character is one of the most powerful villains in the Marvel Universe. He's certainly one of the most grandiose. He exists on sort of a galactic scale. He's an alien being, he's from a race called the Eternals, who pretty much live forever. They are what ancient man thought of as Gods," Brevoort said.

"Thanos is a nihilist. He worships and loves death almost as a person ... he will almost court her. In the course of this story, there were six items of power, six gems that were the Infinity Gems. ... Thanos went on a quest throughout the universe to gather them together and form them into the Infinity Gauntlet, which he wore on his hand and made him omnipotent."

What did he do with that unlimited power in the comics?

"His first act was to wipe out 50 percent of the beings in the universe as sort of a sacrifice to death. One day, suddenly half of the people in the universe vanished or dropped dead. This became an enormous struggle that not just the Avengers, but every superhero on Earth, everybody that was left had to grapple with. ... Because Thanos presented a threat to everybody. He was so absolutely unstoppable. Ultimately, the good guys won and it all turned out okay," Brevoort added.