Buffy The Vampire Slayer Cast: Where Are They Now?
2. Alyson Hannigan
The Role: Willow Rosenberg, the super intelligent (if dorky) high-school friend of Buffy and Xander, who becomes one of the most powerful characters in the entire series (although, unlike with, say, Angel/Angelus, the villainous version definitely isn't better).
Where Is She Now? Alyson Hannigan was already making a name for herself outside of the show while it was on, starring in American Pie 1, 2, and Wedding. Since it ended, it's probably a toss-up between her and former on-screen boyfriend Seth Green as to who has been the most successful former cast member.
The reason of that, of course, is that she went on to star on hit sitcom How I Met Your Mother, which stands as one of the best sitcoms of the last ten years, garnering critical acclaim, Emmy and Golden Globe awards, and a legion of fans, with Hannigan's Lily Aldrin a big part of that success.
Outside of HIMYM she reprised her role as Michelle in American Reunion, and next year she'll be in the movie Modern Love. She is also married to Alexis Denisof, who played Wesley on both Buffy and Angel.