See then-and-now pictures of the Buffy the Vampire Slayer cast, including Sarah Michelle Gellar, Alyson Hannigan, Nicholas Brendon, and David Boreanaz, are now
Alyson Hannigan: Then
After appearing in several TV roles, Hannigan came into her own as Buffy's nerdy best friend Willow Rosenberg. Willow went from being a bookworm with a crush on her pal Xander to a Wiccan to a lesbian to season 6's Big Bad. She ended up saving the world from a massive apocalypse in the series finale.