We have been informed for several years by Marvel, Disney and not least by James Gunn himself that Guardians of the Galaxy was and is his work alone. This while the bulk of the script for the first film was actually not written by Gunn but by Marvel's Nicole Perlman, who had to get her elbows out to ensure that her name was not erased from the film when it was time to finish editing and hit the cinemas.
Nicole was right, her name is in the end credits of the first Guardians film and to celebrate she apparently organised a party which she named "Fuck James Gunn". This is featured in the recently released behind-the-scenes book MCU: The Reign of Marvel Studios.
The screenwriter behind Thor, Zack Stentz, said:
"Nicole had to knife-fight for her credit on Guardians of the Galaxy. But she is probably the preeminent female action tent pole writer now because she was the first woman to have her name on not just a Marvel movie, but on a Marvel movie that people really love."
Thanks, GameRant.