Alyson Hannigan

Alyson Lee Hannigan is an American actress and television presenter born on March 24, 1974. She is best known for her television roles as Willow Rosenberg in the supernatural drama series Buffy the Vampire Slayer and Lily Aldrin in the sitcom How I Met Your Mother. She is also widely recognized for playing Michelle Flaherty in the American Pie film franchise and for hosting the magic competition show Penn & Teller: Fool Us.

Hannigan was born in Washington, D.C., as the only child of Emilie Haas, a real-estate agent, and Alan Hannigan, a Teamsters trucker. She has Irish ancestry through her father and is Jewish through her mother. After appearing in commercials starting at age four, she grew up in Atlanta, Georgia, before moving to Hollywood at age 11. She attended North Hollywood High School and later California State University, Northridge, where she joined the Alpha Chi Omega sorority and earned a psychology degree. As a teenager, she also babysat for Bob Saget's children.

Hannigan made her film debut with supporting roles in Impure Thoughts (1986) and My Stepmother Is an Alien (1988), earning a Young Artist Award nomination for the latter. From 1989 to 1990, she had her first regular television role in the ABC sitcom Free Spirit, receiving another Young Artist Award nomination. Her breakout came in 1997 when she was cast as teenage witch Willow Rosenberg on Buffy the Vampire Slayer.

Hannigan played Willow in every episode of Buffy the Vampire Slayer from 1997 to 2003, winning a Saturn Award and a Teen Choice Award, while also guest starring on its spin-off, Angel. She joined the American Pie franchise as Michelle Flaherty in 1999, appearing in all four main films through 2012. Her work in the film series earned her a Young Hollywood Award and four Teen Choice Award nominations. In 2004, she made her West End stage debut in When Harry Met Sally...

From 2005 to 2014, Hannigan starred as kindergarten teacher Lily Aldrin on the CBS sitcom How I Met Your Mother, winning two People's Choice Awards. Her other projects during this period included the parody film Date Movie (2006), a recurring guest role on Veronica Mars, and a campaign video promoting breast cancer screenings for Stand Up 2 Cancer.

Hannigan hosted Penn & Teller: Fool Us from 2016 to 2023 and voiced Claire Clancy in the animated series Fancy Nancy from 2018 to 2022. Her additional screen credits include You Might Be the Killer (2018), Kim Possible (2019), Flora & Ulysses (2021), and Solo Mio (2026). In 2023, she finished in fifth place on season 32 of Dancing with the Stars.

Hannigan married actor Alexis Denisof on October 11, 2003. The couple reside in Encino, Los Angeles, with their two daughters.