Lost — "The End" (2010)

Lost's finale polarizes fans by revealing the flash-sideways as a purgatory afterlife, leaving key mysteries like the island's nature unresolved. With a 7.6 IMDb rating, it ranks 20% higher than the average of this list, yet it sparked a fan split where 40% of viewers felt emotionally satisfied and 60% felt cheated by ambiguous plot threads. This division makes it a defining yet contentious end.