Alyson Hannigan 1989, her first regular role on a TV series came when she was cast in the short-lived ABC sitcom "Free Spirit". As a teenager, Hannigan babysat for the children of her future "How I Met Your Mother" costar, Bob Saget. In 1997, Hannigan was cast to play Willow Rosenberg, Buffy Summers' best friend, on the television series "Buffy the Vampire Slayer". The show became a success, and Hannigan gained recognition, subsequently appearing in several films aimed at teenaged audiences, including "American Pie" (1999), "Boys and Girls" (2000), "American Pie 2" (2001), and "American Wedding" (2003). She also had a guest
Satsu (Buffy the Vampire Slayer) Satsu (Buffy the Vampire Slayer) Satsu is a fictional character created by Joss Whedon for "Buffy the Vampire Slayer Season Eight", a comic book continuation of the television series "Buffy the Vampire Slayer". Introduced as one of the strongest Slayers, she has a close relationship with her mentor Buffy Summers. Satsu develops romantic feelings for Buffy, and the two have a brief sexual relationship. She becomes the leader of her own Slayer squadron in Tokyo, and forms a friendship with fellow Slayer Kennedy during her performance review. She also makes a minor appearance in "Buffy the Vampire Slayer Season Ten".