<Tr> <Th> Spouse (s) </Th> <Td> Alexis Denisof (m . 2003) </Td> </Tr> <Tr> <Th> Children </Th> <Td> </Td> </Tr> <P> Alyson Lee Hannigan (born March 24, 1974) is an American actress . She is best known for her roles as Willow Rosenberg on the television series Buffy the Vampire Slayer (1997--2003), Lily Aldrin on the sitcom How I Met Your Mother (2005--2014), and Michelle Flaherty in the American Pie film series (1999--2012). </P> <P> Hannigan was born in Washington, D.C., the only child of Emilie (Posner) Haas, a real estate agent, and Alan Hannigan, a Teamsters trucker . Her father is of Irish ancestry and her mother is Jewish . </P>

Who plays willow in buffy the vampire slayer