Robert Downey Jr. has signed up for two more "Avengers" films.Marvel announced today that the actor will reprise his role as Iron Man/Tony Stark for "The Avengers 2" and "The Avengers 3." Downey Jr. has played the character in a trilogy of "Iron Man" films, as well as the first superhero ensemble "Avengers" film, which made $2.7 billion worldwide.Joss Whedon is to return as director of the next "Avengers" film. He is writing the screenplay now. Production is to begin in March, with a theatrical release in May 2015.The 48-year-old actor had previously suggested "Iron Man 3" might be his last spin in a stand-alone "Iron Man" film. Marvel's announcement made no mention of an "Iron Man 4" release.