Cosmo is a Golden Retriever/Labrador cross-breed dog that was a former test animal of the Soviet Space Program.

He was launched into Earth's orbit as part of an experiment at some point during the 1960's, but ended up drifting off into deep space. Somewhere along the line, Cosmo was mutated and developed telepathic abilities, and he wound up arriving in Knowhere. He eventually took the position as head of security of the space station.