As the old saying goes, there are no small roles, only small actors - which is why cinema history is filled with supporting characters that stole the movie. It's not uncommon for a sidekick or supporting character to steal the show, as they're typically given plenty of scenes where they get to be the comic relief while the protagonist remains a bit more serious. It's a lot harder to show up for a scene or two, leave it all on the floor, and somehow do enough to enter the cultural conversation - or even star in a sequel.
Sometimes, these small characters overshadowed their film's reputation even though they were in barely more than a single scene. Whether it's Will Ferrell yelling in a kimono or Bill Murray chasing a gopher, these are the characters that audience members think back to the most, even though they were hardly in the movie at all.