The Guardians of the Galaxy are made up of some lovable yet rather odd characters, including the endearing combo of Rocket Raccoon and Groot. Both characters are synonymous with their voice actors Bradley Cooper and Vin Diesel, but in Rocket's case, there is one more individual deserving of credit.
That would be Sean Gunn, who actually does the performance work for the character on set. He's also played Kraglin, a member of the Ravagers, but during principal photography, he is responsible for setting the base for all of Rocket's movements and performance animations. When asked why Bradley Cooper doesn't fill this role, director James Gunn explained that there are things a motion reference actor is just more cut out for (via CinemaBlend).
"Sean Gunn is not a stand-in. He is a motion reference actor. That means we film everything Sean does on set as Rocket. We film it. I don't stop doing takes of him until we get the performance right and then we use that performance as a basis for much of Rocket's acting. And he does a fantastic job in that role. He knows it. He understands it. And also very important, Sean is able to physically do something most actors aren't able to do, which is waddle around on all fours. He's always been an incredibly limber guy that can to do a lot of strange physical things. And the fact that he's able to waddle around on his legs all day long at the exact height of Rocket is quite a feat and quite, quite difficult."
There is definitely an art to portraying these characters on set, and the combintion of Gunn's perfroance and Coopers voice seems to have worked flawlessly.
Set to the backdrop of ‘Awesome Mixtape #2,’ Marvel’s Guardians of the Galaxy Vol. 2 continues the team’s adventures as they traverse the outer reaches of the cosmos. The Guardians must fight to keep their newfound family together as they unravel the mysteries of Peter Quill’s true parentage. Old foes become new allies and fan-favorite characters from the classic comics will come to our heroes’ aid as the Marvel cinematic universe continues to expand.
Guardians of the Galaxy Vol. 2 is written and directed by James Gunn (Slither). The film marks the return of the original Guardians, including Chris Pratt (Jurassic World) as Peter Quill/Star-Lord; Zoe Saldana (Star Trek Into Darkness) as Gamora; Dave Bautista (Spectre) as Drax; Vin Diesel (Furious 7) as the voice of Groot; Bradley Cooper (American Sniper) as the voice of Rocket; Michael Rooker (Jumper) as Yondu; Karen Gillan (The Big Short) as Nebula; and Sean Gunn (Gilmore Girls) as Kraglin. New cast members include Pom Klementieff (Oldboy), Elizabeth Debicki (The Great Gatsby, Everest), Chris Sullivan (The Knick, The Drop) and Kurt Russell (The Hateful Eight, The Thing).
Next up for Marvel is Guardians of the Galaxy Vol. 2 on May 5, 2017. Spider-Man: Homecoming lands on July 7, 2017, followed by Thor: Ragnarok on November 3, 2017. After that Black Panther debuts on February 16, 2018, while Avengers: Infinity War hits theaters on May 4, 2018. Ant-Man and the Wasp is slated for July 6, 2018, followed by Captain Marvel on March 8, 2019.