Alyson Lee Hannigan was born on March 24, 1974, in Washington, DC, the only child of real estate agent Emilie Posner Haas and Teamsters trucker Alan Hannigan. She began acting as a child, appearing in Impure Thoughts (1986) and My Stepmother Is an Alien (1988). She later attended California State University, Northridge, earning a bachelor’s degree while continuing to pursue acting roles.

Hannigan’s breakthrough came as Willow Rosenberg on Buffy the Vampire Slayer from 1997 to 2003. This was followed by roles in the American Pie film franchise starting in 1999. From 2005 to 2014, she starred as Lily Aldrin on CBS’s How I Met Your Mother. She also voiced Claire Clancy on Disney Junior’s Fancy Nancy from 2018 to 2022.

In 2016, Hannigan became the host of Penn & Teller: Fool Us on The CW, succeeding Jonathan Ross for Season 3. She hosted the magic competition series for seven seasons until 2023, when Brooke Burke took over. That same year, she competed on Season 32 of Dancing with the Stars, partnered with professional dancer Sasha Farber, reaching the finale. She continues to be active in the industry, with voice and acting roles in both film and television.