It was revealed in early August 2006 by Marvel that an Avengers is in development. It was later revealed that Zak Penn, writer of X2: X-Men United, X-Men: The Last Stand and Elektra will be writing the script for the live-action film.

Iron Man director Jon Favreau said he would like to direct a film adaptation of the Avengers. This would be a crossover to fictional universes in other upcoming Marvel films such as the Incredible Hulk, Thor and Captain America. He also explained that Marvel has told him that "they're pretty clear on wanting to do it with the actors who've established the roles or to not do it at all." He continued, "I think it’s a good idea if you use the characters established in the other franchises that then come together for an event."

On May 5, 2008 during Marvel's Quarter 1 webcast, it was announced that the Avengers will be released in July 2011.