Fan Casting Suspiciously Similar Substitute in Sort by Tropes

A character who joins the cast as a replacement for a character who has left the main cast despite being integral to the plot or concept of the series. Invariably, this character fills the Stock Character slot left vacant by the departed, whether that be comic relief, intellectual, or musclebound bruiser. The reasons why the original character left can vary from narrative reasons (Face–Heel Turn, Killed Off for Real, Career-Ending Injury) to real life availability of the performer (Role-Ending Misdemeanor, Troubled Production), and it was deemed easier to create a new character rather than ignoring the current storyline to bring them back or just replacing the performer.