Scrubs — Season 9 (2010)

Scrubs' ninth season betrays its legacy by masquerading as a final season when it's really a spin-off, replacing core characters with new med students—a move that earned a 58% score on Rotten Tomatoes, 20 points lower than any prior season. Unlike #9's finale that at least respects its narrative arc, this installment retroactively taints a beloved series. Creator Bill Lawrence himself disowns it, calling season 8's finale the true ending. Fans abandoned the show in droves, with average viewership sinking to 4.2 million, less than half of season 8's numbers.