Following this morning’s first leak of what Thanos looks like in Guardians of the Galaxy, there have been some people surprised that the Mad Titan appears in a movie based on the Marvel Cosmic Universe and dealing with the Infinity Stones. These people weren’t expecting to see him until The Avengers: Age of Ultron, and if that’s their expectation for that film, they will probably be disappointed.
In an interview with Comic Book Resources, Marvel Studios head Kevin Feige says that Thanos has no part in Age of Ultron:
Are we going to get any Thanos in “Avengers 2?” There was some of him in “Guardians in the Galaxy,” and it was clear that when he gets a movie, it’s going to be a big deal.
Right. I’m glad it feels that way. That’s the idea. He’s not a part of “Avengers 2.”
We’ve explained why this is so in the past, and it makes sense with how some trilogies tell their stories. In Star Wars the Death Star was a threat in the first movie, but not the second, but when Jedi rolled around there was another Death Star. The League of Shadows was the villain in Batman Begins, while The Dark Knight had no real presence for them, but they were back in the spotlight in The Dark Knight Rises.
The Avengers will be the same. You won’t see Thanos in the second movie, but the third film is where they’ll learn he was the one behind the Battle of New York in their first outing.