Marvel is in early talks with Bradley Cooper to voice Rocket Raccoon in Guardians of the Galaxy, a role both Adam Sandler or Jim Carrey were previously rumored to be up for. http://movieweb.com/does-marvel-want-bradley-cooper-as-rocket-raccoon-in-guardians-of-the-galaxy/News of Bradley Cooper's casting broke last night.
Elizabeth Olsen's http://movieweb.com/is-elizabeth-olsen-scarlet-witch-in-the-avengers-age-of-ultron/talks are much further along, with the actor up for the role of Scarlet Witch in The Avengers: Age of Ultron. The role was tailor-made for actress Saoirse Ronan, according to director Joss Whedon, who wrote the script with her in mind. When Ronan passed on the project, Marvel next sought out Elizabeth Olsen.
Guardians of the Galaxy is currently shooting in London, with a cast headlined by Chris Pratt, Dave Bautista and Zoe Saldana. Vin Diesel is currently in talks for the other main voice role of Groot. Unlike Rocket Raccoon, his character only has one line of dialogue. It's not likely that either actor will be performing motion capture as the film continues to shoot.
At this time, Marvel has no comment.