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
Darla (Buffy the Vampire Slayer) Darla (Buffy the Vampire Slayer) Darla is a recurring fictional character created by Joss Whedon and played by Julie Benz in the first, second, and fifth seasons of the American supernatural television series "Buffy the Vampire Slayer". The character later appeared in the "Buffy" spin-off series "Angel", making at least one appearance in every season. She made her last television appearance in 2004, appearing as a special guest star in the fifth and final season of "Angel". Darla is introduced in "Welcome to the Hellmouth", the first episode of "Buffy the Vampire Slayer", in 1997. It is revealed early on