Use stream of consciousness to answer the following. 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).

Answer this question based on the passage: who played lily in how i met your mother?
To answer the above question, the relevant sentence is: 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). Final answer: Alyson Lee Hannigan.