Phase One of the Marvel Cinematic Universe (MCU) is a group of American superhero films produced by Marvel Studios based on characters that appear in publications by Marvel Comics. The MCU is the shared universe in which all of the films are set. The phase began in May 2008 with the release of Iron Man and concluded in May 2012 with the release of The Avengers. Kevin Feige produced every film in the phase, with Avi Arad also producing Iron Man and The Incredible Hulk, and Gale Anne Hurd also producing The Incredible Hulk. The films star Robert Downey Jr. as Tony Stark / Iron Man in Iron Man and Iron Man 2, Edward Norton as Bruce Banner / Hulk in The Incredible Hulk, Chris Hemsworth as Thor in Thor, and Chris Evans as Steve Rogers / Captain America in Captain America: The First Avenger. All returned to star in the ensemble film The Avengers except for Norton, who was replaced by Mark Ruffalo. Samuel L. Jackson has the most appearances in the phase, starring or making cameo appearances as Nick Fury in five of the films.
