Spin-off characters can come from anywhere - from the sidekick of a figurehead character to the “friend of a friend” who shows up in a one-off episode - and are the last people audiences would expect to get a series or movie. That being said, expected spin-offs (e.g., the Friends spin-off, Joey) often fail miserably. Minor side characters get spin-offs for a multitude of creative/commercial reasons.
Yes, many exist simply because Hollywood ran out of ideas, and the powers that be want more of the cow’s milk. Others satisfy a thirst for more from an adolescent franchise, leading fans off the beaten trail with stories that enrich and improve upon what came before in exciting ways. This list will be a roundup of TV shows and movies that spin off from existing franchises but focus on a strange or unlikely background character.