The plotline for the Marvel Cinematic Universe will culminate in "Avengers 3." Marvel Studios President Kevin Feige has built up Thanos for years-and it will all come to a head in the third installment.

Thanos has already been teased even before the Avengers. Comic book fans know all too well that the 'glove' in Odin's collection is the Infinity Gauntlet-one of the best crossover storylines that Marvel has executed. Any sign of the Gauntlet means Thanos is not far behind.

The Infinity Gems, despite the different names, are also tell-tale signs. Thus, when Thanos was teased in the first Avengers movie, comic fans were not surprised but the confirmation excited them just the same.

To make it official, Kevin Feige stated in a Q&A session at Cine Europe in Barcelona (from JoBlo):

"If you remember we had a tag scene in Thor: The Dark World where Benicio Del Toro showed up for the first time as The Collector, so that was our way of saying the Guardians and the other Marvel characters inhabit the same reality and the same universe. In particular, there's a villain in this film, that comic fans know as Thanos, that moviegoers will begin to learn more and more about in the coming years. He appeared at the very end of the first Avengers film, when he turned into camera and smirked, and we realised he was the person behind the alien army that Loki teamed up with to terrorise New York City, and that the Avengers had to fight. We see him again in this movie [Guardians], we learn a little bit more about him in this movie, and he - and his band of followers - is the biggest piece of connective tissue that will eventually lead us back into Avengers films in the future."

The connection between films has been Marvel's recipe for success. The near-seamless execution and how it doesn't interfere so much with the standalone films is an approach the other studios fail to emulate.

Speaking of other studios, both the X-men and Avengers are on its way to fighting the toughest villains of their canon. What's next after Avengers defeat Thanos and the X-Men defeat Apocalypse? How about a crossover? Feige is cautious but not dismissive:

"It would be great, I think, to be able to have all of the Marvel characters interact one day, in a single movie with Marvel Studios, [but] I don't think that'll happen anytime soon. Fox is doing very well - 'Days Of Future Past' just came out, was a big hit, was a very, very good movie. As long as they keep doing that they'll be able to keep those rights."

Very diplomatic, matter-of-fact answer, but he adds: "So I wouldn't say anything's impossible, I've been at Marvel for almost 14 years now, and it's a very different company today than when it was a near bankrupt company just trying to get a foothold in movies when I started. So I always say nothing is impossible but I'm not sure that's going to happen any time soon."