Gallery: Avengers premieres

The cast of 'Marvel Avengers Assemble', from left to right, Mark Ruffalo, Tom Hiddleston, Robert Downey Jr, Jeremy Renner, Scarlett Johansson, Cobie Smulders, Chris Hemsworth and Clark Gregg, assemble for a group photograph ahead of the European Premiere of the film at a west London cinema, Thursday, April 19, 2012. (AP Photo/Joel Ryan)

Cobie Smulders arrives for the European Premiere of 'Marvel Avengers Assemble', at a west London cinema, Thursday, April 19, 2012. (AP Photo/Joel Ryan)

U.S actress Scarlett Johansson arrives for the European Premiere of 'Marvel Avengers Assemble', at a west London cinema, Thursday, April 19, 2012. (AP Photo/Joel Ryan)

Actor Mark Ruffalo attends the premiere of "The Avengers" during the 2012 Tribeca Film Festival on Saturday, April 28, 2012 in New York. (AP Photo/Evan Agostini)

Actors Chris Hemsworth, left, Scarlett Johansson, center, and Mark Ruffalo pose during a photocall of the movie "The Avengers", in Rome, Saturday April 21, 2012(AP Photo/Alessandra Tarantino)

From Left, actors Chris Hemsworth, Tom Hiddleston, Scarlett Johansson and Mark Ruffalo pose during a photocall of the movie "The Avengers", in Rome, Saturday April 21, 2012(AP Photo/Alessandra Tarantino)

Actress Scarlett Johansson poses for photographers during the Russian premiere of Marvel's The Avengers in Moscow, Russia, Tuesday, April 17, 2012. (AP Photo/Misha Japaridze)

Actress Scarlett Johansson poses for photographers during the Russian premiere of Marvel's The Avengers in Moscow, Russia, Tuesday, April 17, 2012. (AP Photo/Misha Japaridze)

Actor Chris Hemsworth attends the premiere of "The Avengers" during the 2012 Tribeca Film Festival on Saturday, April 28, 2012 in New York. (AP Photo/Evan Agostini)

In this film image released by Disney, Scarlett Johansson portraying Black Widow, left, and Jeremy Renner, portraying Hawkeye, are shown during the filming of Marvel's "The Avengers." (AP Photo/Disney, Zade Rosenthal)

U.S actor Jeremy Renner arrives for the European Premiere of 'Marvel Avengers Assemble', at a west London cinema, Thursday, April 19, 2012. (AP Photo/Joel Ryan)

Australian actor Chris Hemsworth and wife Elsa Pataky arrive for the European Premiere of 'Marvel Avengers Assemble', at a west London cinema, Thursday, April 19, 2012. (AP Photo/Joel Ryan)

A general view of the setting for the European Premiere of 'Marvel Avengers Assemble', at a west London cinema, Thursday, April 19, 2012. (AP Photo/Joel Ryan)

U.S actress Scarlett Johansson signs autographs for fans as she arrives for the European Premiere of 'Marvel Avengers Assemble', at a west London cinema, Thursday, April 19, 2012. (AP Photo/Joel Ryan)

Clark Gregg arrives for the European Premiere of 'Marvel Avengers Assemble', at a west London cinema, Thursday, April 19, 2012. (AP Photo/Joel Ryan)

Actor Robert Downey Jr. attends the premiere of "The Avengers" during the 2012 Tribeca Film Festival on Saturday, April 28, 2012 in New York. (AP Photo/Evan Agostini)

Actress Scarlett Johansson's star on the Hollywood Walk of Fame is seen in Los Angeles, Wednesday, May 2, 2012. Johansson stars in the upcoming film "The Avengers". (AP Photo/Matt Sayles)

U.S actor Robert Downey Jr arrives for the European Premiere of 'Marvel Avengers Assemble', at a west London cinema, Thursday, April 19, 2012. (AP Photo/Joel Ryan)

Actor Chris Hemsworth attends the premiere of "The Avengers" during the 2012 Tribeca Film Festival on Saturday, April 28, 2012 in New York. (AP Photo/Evan Agostini)

Actress Scarlett Johansson signs autographs for fans after receiving a star on the Hollywood Walk of Fame in Los Angeles, Wednesday, May 2, 2012. Johansson stars in the upcoming film "The Avengers". (AP Photo/Matt Sayles)

U.S actor Robert Downey Jr arrives for the European Premiere of 'Marvel Avengers Assemble', at a west London cinema, Thursday, April 19, 2012. (AP Photo/Joel Ryan)

From left, actors Jeremy Renner, Robert Downey Jr., actress Scarlett Johansson, actors Chris Hemsworth, Tom Hiddleston and Mark Ruffalo pose for photographers during the Russian premiere of Marvel's The Avengers in Moscow, Russia, Tuesday, April 17, 2012. (AP Photo/Misha Japaridze)

Actor Jeremy Renner signs autographs for fans after actress Scarlett Johansson, not pictured, received a star on the Hollywood Walk of Fame in Los Angeles, Wednesday, May 2, 2012. Renner and Johansson star in the upcoming film "The Avengers". (AP Photo/Matt Sayles)

Actress Scarlett Johansson poses for photographers after receiving a star on the Hollywood Walk of Fame in Los Angeles, Wednesday, May 2, 2012. Johansson stars in the upcoming film "The Avengers". (AP Photo/Matt Sayles)

Actress Scarlett Johansson poses for photographers after receiving a star on the Hollywood Walk of Fame in Los Angeles, Wednesday, May 2, 2012. Johansson stars in the upcoming film "The Avengers". (AP Photo/Matt Sayles)