Alyson Lee Hannigan (born March 24, 1974) is an American actress. She is best known for her role as Willow Rosenberg on the television series Buffy the Vampire Slayer. She currently plays Lily Aldrin on the CBS sitcom How I Met Your Mother. She also played flautist Michelle Flaherty-Levenstein in three American Pie films.
Hannigan was born in Washington, D.C., the daughter of Emilie Posner, a real estate agent, and Al Hannigan, a truck driver. Hannigan is Jewish on her mother's side, and also has Irish ancestry. Her parents divorced a year after her birth and she was raised mostly by her mother in Atlanta.
Although Hannigan had appeared in an industrial film for "Active Parenting" as a baby, as well as starred in a commercial for the Duncan Hines cookie mix in 1978, it was not until she moved to Los Angeles, California, in 1985 that she formally began her acting career. Living with her mother and attending North Hollywood High School, she successfully auditioned for agents while visiting her father in Santa Barbara. After attending North Hollywood High School she attended California State University, Northridge.
Hannigan's first major film role was in My Stepmother Is an Alien, a