Seinfeld — "The Finale" (1998)

The worst-rated finale in television history—only 54% of viewers approved—Seinfeld's "The Finale" turns the show's signature apathy into a courtroom lecture, a choice that outperforms even #7 for sheer disappointment because it wastes 76 million viewers' goodwill. The four leads are tried for their callousness, a meta-commentary that lands as preachy rather than funny, and the data proves it: the episode's Nielsen rating plunged 22% from the previous season's average, making it the most hated send-off of any top-rated sitcom. Unlike the merely unsatisfying #6, this finale actively retrofits the series' charm into a flaw.