Considering the stellar location of Marvel's Guardians of the Galaxy, it's not a surprise that several of its core heroes are otherworldly. As filming commenced, director James Gunn was faced with the problem of putting a CGI-based, anthropomorphic raccoon alongside a sentient tree and three human actors.

To get Bradley Cooper's Rocket Raccoon just right, Gunn and his team brought one of the garbage bandits on set. Named Oreo, the little critter informed about one fifth of Rocket's composition.    

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"We needed a raccoon to study how he looked and his behavior, so that our on-screen raccoon, which is generated through CGI will be realistic," Gunn explained to the magazine Small Furry Pets (via Comic Book Movie). "Our Rocket is based on a combination of our voice actor, Bradley Cooper, our on-set actor, my brother Sean Gunn, the movements and behavior and look of Oreo, as well as my own animation."

Making Rocket look and move like the raccoons viewers are familiar with was only half the battle, however. Described by Zoe Saldana (Gamora) as an "antihero hero movie," Guardians' saviors have fairly dark and complicated backgrounds. While Cooper's voice acting will be the major conveyor of this information, Gunn wants to make sure that Rocket's history and demeanor are abundantly clear to the audience.

"He is most representative of the Guardians in the fact that he's this little mangled beast that was taken and experimented on and torn apart and put back together, and we have to feel that character's soul," Gunn told Total Film. "If we see his plight, and see why he's such an angry little guy, then the movie will work."

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Considering the work put into Rocket's creation and the long hours put in by Cooper at the studio, it will be fairly disappointing if the character fails to help the audience become attached to the Guardians tale.  

Although Guardians of the Galaxy will not hit theaters until Aug. 1, fans can get a first look at The Collector (Benicio Del Toro) in the mid-credit scene form November's Thor: The Dark World (see video below).