In the late '90s, Willow Rosenberg (played by Alyson Hannigan) arose as one of the most beloved characters on Buffy the Vampire Slayer. Her gradual evolution from an introverted bookworm into a badass spell-casting witch — later goddess — made her more than just Buffy's damsel-in-distress sidekick. Willow's coming-of-age story made her super relatable and fun to watch. Her friendship with Buffy was nothing to scoff at, either. Between battling demons and other villains, Willow served as a confidant and voice of reason for the vampire slayer. With that (and Buffy's 20th anniversary) in mind, we've rounded up all the reasons Willow is the kind of best friend every girl truly needs in her squad.