Why Didn’t Sean Gunn Voice Rocket in the MCU Instead of Bradley Cooper?

When people talk about the behind the scenes talent on Guardians of the Galaxy, they usually refer to writer-director James Gunn, who often interacts with fans directly on social media. However, he’s not the only Gunn who works on the movies. 

There’s also James’ brother Sean Gunn, who is the live stand-in on set for Rocket Raccoon before the CGI artists do their work and the sound team lays in Bradley Cooper’s voice track. Marvel fans think Gunn’s considerable work should be more widely recognized. 

What does Sean Gunn do for Marvel? 

Sean Gunn
Sean Gunn | Jerod Harris/Getty Images

According to an interview with EW, Gunn didn’t get to work with Marvel just because he was family. He was particularly flexible, in more ways than one. As James explained, “When Sean was 12 years old, he would amaze people who came over to the house by taking off all his clothes, and standing there in his tighty-whitey underwear, and fitting himself through a wire hanger without bending it.”

Now that’s something most people haven’t thought about doing, much less been actually able to do it. But that flexibility proved valuable, because it allowed Sean to crouch comfortably at what would be Rocket’s eyeliner so the other actors could react believably with him.

The Gunns eschewed the all-too-common approach of having actors respond to inanimate objects like tennis balls, or to nothing at all. So Gunn squats and stretches, all while wearing a motion capture suit that forms the basis of the effects work 

Fans on a Reddit thread reacting to a behind the scenes photo of Gunn were suitably impressed, with one saying, “Sean Gunn is not a young man. All I can see in this picture is his knees–crouching like that for any length of time is a biggest physical feat I’ve ever seen on an Avengers set.”  Now that’s saying something. 

How come Bradley Cooper voiced Rocket and not Sean Gunn?

The “obvious” explanation as to why Sean Gunn does not provide the final voice for Rocket may be that James didn’t want to take nepotism too far, but it’s actually not that simple.

Gunn admits it’s “strange” to hear Cooper’s voice after Gunn had already done so much physical work, but he told EW, “I never did the job because I thought it would get me a lot of attention. I did the job because I wanted the movie to be as good as it could possibly be.”

Fans on a different Reddit thread think James deserves more credit than he actually gets, or that he gives himself. One said, “Sean Gunn is contributing almost 50% of the work that takes into making Rocket come to life. He is also present on set which is definitely more work than recording lines in a booth. Don’t get me wrong, Bradley Cooper is BRILLIANT as the voice of Rocket and he has owned the voice, but Sean Gunn puts in just as much work into bringing the character to realization.”

Such a clamor is understandable because Gunn doesn’t just stand in for Rocket. He has done the same for Thanos, and he actually appeared on camera as the villain-turned-hero Kraglin. He will at the very least reprise the mo-cap role of Rocket whenever Guardians of the Galaxy Vol. 3 finally gets off the ground. 

Celebrity voices are a relatively recent phenomenon


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For most of animation history, doing voice work wasn’t a particularly lucrative gig. Especially when Walt Disney was still living, people didn’t get to Disney movies because a certain actor did a voice. Back then, A-list stars rarely if ever provided voices for animation. According to YouTube essayist Lindsay Ellis, That all changed when Robin Williams became known as the voice of the Genie in Aladdin in 1992. 

Ironically, Williams did the voice on the condition that his name not be used to sell the movie. It eventually was, and he and Disney parted ways for a time as a result. But after Williams’ work, the genie was truly out of the bottle. Not only did more celebrities start doing voice work, but some studios, particularly DreamWorks Animation, began using celebrities’ names as a selling point.  

Some may think Cooper got the job voicing Rocket because he’s a famous actor and there may be some truth to that, but it’s not unreasonable to ask if that many people went to see the first Guardians of the Galaxy because Bradley Cooper did the voice. WIth Marvel, it’s arguably the characters and the franchise that matter more than the actual actors.