Alyson Hannigan was already relatively well-known for her role as Willow Rosenberg on Buffy the Vampire Slayer. While she played a lesbian (opposite Michelle Trachtenberg) on Buffy, her sexuality was a bit wackier in American Pie. Who could forget her jaw-dropping, "This one time, at band
camp," revelation at Stifler's party, which made Jason Biggs spit out his drink (and lose his virginity).
While she did reprise her role as Michelle Flaherty in American Pie 2, American Wedding, and American Reunion, most people came to know her as Lily Aldrin on How I Met Your Mother. Hannigan starred on the popular sitcom for nine seasons opposite Jason Segal before the series ended in 2014.
While she hasn't done much acting since then, for the past year, she has been hosting Penn and Teller: Fool Us, returning for their new season in a few weeks. For the most part, Hannigan seems to be focusing on raising her two daughters with husband Alexis Denisof, whom she met on Buffy the Vampire Slayer. The two have remained close friends with Joss Whedon—acting as godparents to his son, Arden—and giving them the ultimate nerdy bragging rights.