1. 'The Body' (Season 5, Episode 16)
While many bigger-budget, higher-profile shows since Buffy have tried to tackle existential truths – Lost, Mad Men, The Sopranos – this hour of television deals us nothing short of the meaning of life in one devastating blow. By this point, Buffy has saved the world from the apocalypse so much that it's become a joke among her and her friends. Together, they have slayed scores of vampires, cast and reversed dozens of spells, played with the boundaries of life and death over and over. In "The Body," however, they are powerless in the face of an unexpected aneurysm after Buffy's mother has surgery to remove a tumor. In the first scene, she finds her parent's lifeless body on the sofa. After years of handily dispatching with vampires and monsters, we suddenly see a regular young woman who needs paramedics, her father figure Giles, and her friends – not to help her fight, but to help her deal. Long takes and long silences, along with Whedon's brilliance with everyday details – a lingering shot of a paper towel soaking up Buffy's vomit on the living room floor, her friend Willow' s obsession with getting her hospital outfit just right – make this whole episode a gut punch. And its conclusion is the most unpopular thought in popular culture: We all die, it's no one' s fault, and there's nothing we can do about it.