Cosmo is a fictional character in Marvel Comics and the Marvel Cinematic Universe. He first appeared in the comics in Nova #8 in 2008 and in the Marvel Cinematic Universe in the 2014 film Guardians of the Galaxy.
In the comics, Cosmo is a telepathic and telekinetic dog who was sent into space by the Russian government during the Cold War. He eventually became the head of security for Knowhere, a space station built inside the severed head of a Celestial. Cosmo is known for his calm demeanor and leadership skills, as well as his ability to read and control minds.
In the Marvel Cinematic Universe, Cosmo is a minor character who appears briefly in the first Guardians of the Galaxy film. He is depicted as a telepathic dog who serves as the head of security for the Collector's museum on Knowhere. He communicates with the Guardians of the Galaxy through telepathy and assists them in their mission to stop Ronan the Accuser.
Overall, Cosmo is a beloved character in the Marvel Universe for his unique abilities, loyalty, and adorable appearance as a talking space dog.