4. 'The Gift' (Season 5, Episode 22)
The hundredth episode of Buffy had to be a big deal, right? Buffy must save the world yet again, but this time the season ended in what appeared to be a definitive, no-turning-back way: She sacrifices herself to save her sister Dawn, and by extension, humanity. The WB called it a “series finale," and it makes sense as an ending – the point of a slayer, after all, is to die in service to others, and the moment gives Buffy the heroic sendoff imaginable. But real-life TV business dictated that Sunnydale's best and brightest live again on the rival network UPN, which Buffy's studio, 20th Century Fox Television, had recently bought a large stake (as it were). Significantly, Whedon isn't content to simply use magic to revive his heroine for more fun and games with her friends; her eventual return to the land of the living haunts her through the sixth and seventh seasons, forcing the young woman question the nature and meaning of life. It was a bold gamble that paid off.