<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> 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>
who played willow in buffy the vampire slayer
who played willow in buffy the vampire slayer
Alyson Lee Hannigan
Alyson Lee Hannigan