Alison Lee Hannigan (she changed the spelling of her first name to Alyson when she became an actress) (born March 24, 1974) is an American actress best known for playing Willow Rosenberg in the TV series Buffy the Vampire Slayer. She also appeared in films including, as Michelle Flaherty, American Pie (1999), American Pie 2 (2001) and American Wedding (2003).
Born in Washington, DC, her first film role was in My Stepmother is an Alien (1988). Before that she had done a little television work, mostly commercials, and she went on to do a good deal more including Almost Home, Picket Fences, Roseanne and Touched by an Angel before being chosen for Buffy in 1997. By the final season she was earning $250,000 an episode.