According to James Gunn, the creator(s) of Rocket Raccoon is identified somewhere in Guardians of the Galaxy: Volume 2.
Specifically in the Marvel Cinematic Universe, who created Rocket Raccoon?
@ConceptsComics: So... Who do you think probably created rocket, in all his misery? If you were to have any character, even from the comics, that is.
@JamesGunn: Believe it or not if you’re really really really smart this is hidden somewhere in Vol 2.
In the MCU, Rocket Racoon was created by The High Evolutionary, as evidenced in The Guardians of the Galaxy: Vol 3 (released May 2023).
img src: https://www.looper.com/img/gallery/guardians-3-how-the-high-evolutionary-is-different-from-the-comics/intro-1683216244.jpg
During the events of Vol 3, the Guardians are attacked on their new base, Knowhere, where Rocket is
mortally wounded by Adam Warlock.
Setting off a chain of events where Rocket's in-built tracking and
kill switch
mechanism are triggered.
It was Nebula who interfaces digitally to Rocket's vital functions and accesses his in-built database and discovers a digital signature belonging to "OrgoCorp" as well as a need for a 'keyphrase' (which becomes the Maguffin and plot driver for the story).
The Guardians embark on a mission to determine the origin and creators of Rocket, which leads them to the the discovery of the High Evolutionary and his experiments in OrgoCorp, where he claimed:
I'm not trying to conquer the universe. I'm perfecting it.
During the course of the movie, we experience multiple 'flashbacks' of Rocket's early life (including from before his experiment) where he interacts with the High Evolutionary.
Fun fact: during the experiments, Rocket was designated the label "89P13" ('89' signifying the 89th batch of experiments).
Chances are, it's High Evolutionary, aka Herbert Edgar Wyndham
Evidence is not 100% conclusive but plausible:
The planet that GotG land on after escape from Sovereign fleet and where they meet Ego is called Berhert
That's an anagram of "Herbert" which is High Evolutionary's first name.
Credit: Second Son channel on YouTube
Now, as per the question, Gunn explicitly stated that Rocket's creator was Easter-Egg-hidden in GotG#2 film; and this is the only known possible clue.
Although High Evolutionary had nothing to do with creation of Rocket in the Marvel comics, he is generally very suited to the role:
Although expelled from the university for his single-mindedness, he finally succeeded in evolving his pet Dalmatian Dempsey into a humanoid life form with the intelligence of a chimpanzee.
The two characters did intersect in Marvel comics:
The High Evolutionary appears in the Guardians of the Galaxy animated series, voiced by Nolan North. In the episode "Evolution Rock", he and his insectoid creations have captured Rocket Raccoon, Groot and Captain Marvel to experiment on...
Last, but not least, Twitter account "Rodger Wardell" confirmed this when discussing Guardians of the Galaxy Vol. 3:
Roger Wardell @RogerWardell
Rocket's creator is the High Evolutionary, Drax is in for a big surprise when he discovers his daughter is alive. Rocket also gets a love interest in the form of Lylla. Nebula and Star Lord will grow into closer friends.
3,250 8:34 PM - May 7, 2019
This isn't an official MCU account, but as per comicbook.com,
it previously had a string of Avengers: Endgame leaks last December that all ended up correct in some shape, way, or form.
Who created him as a character?
Rocket Raccoon was "created" as a character by Bill Mantlo and Keith Griffin according to the Hollywood reporter.
Who created him in the comics?
Rocket Raccoon exists within the Marvel Universe Earth-616 continuity. The character has a complicated in-universe back-story. He first appeared in Marvel Preview #7 (June, 1976). Here is the abridged version.
And for the scientific purists among you: It is likely he is a raccoon-like organism, not necessarily a raccoon from EARTH. But for the sake of the non-scientific, the difference is minimal. Star-Lord recognized him as a raccoon and that is what he calls himself.
Who is his creator in the Cinematic Universe?
No one has been able to find the hidden Easter Egg about Rocket yet from the research I've done but I found out (according to Slash Film) James Gunn has commented on the origin of Rocket saying:
“We are going to learn more about where Rocket comes from in the coming sagas. It’s going to be a little different from the comics. We already know a lot about from where he came from. It’s a little bit more horrible than what it is in the comics when you come down to it. We will learn more about that.””
So in the coming films we will learn more about Rocket
According to Nerdist:
That glimpse of Rocket’s backside from the first Guardians of the Galaxy movie already suggested a much darker origin compared to his comic book roots. As originally conceived by Bill Mantlo and Keith Giffen, Rocket lived on a planet called Halfworld alongside other anthropomorphic talking animals like Wal Rus and Blackjack O’Hare. Years later, that fairly peaceful origin was retconned into a new past that established the anthropomorphic animals as experiments at the Halfworld Asylum for the Criminally Insane. Essentially, they were all therapy animals.
According to Screen Rant:
The director previously defended the changes made from the comics, and it’s clear he’s not going to stop making adjustments going forward. The films have already told us that Rocket was experimented on to increase his intelligence and strength, but the reasons have been kept vague. Perhaps in Guardians of the Galaxy Vol. 3, Gunn will show audiences the reasons behind Rocket’s abrasive personality.
After lots of research all I can find are theories about his origin infact FilmTheory have made a great video about it:
It suggests Rocket was a failed Super Soldier experiment and etc.
Rocket is stated in Guardians of the Galaxy (on his criminal record) to have originated from a planet(?) called Halfworld.
There's no indication in the films what (or where) Halfworld is, but this does tie in with his comic origins, as an experiment by the Robots of Halfworld.
