Joss Whedon is an American producer, director, screenwriter, comic book writer, and composer. He is the creator of pop culture phenomenons Buffy the Vampire Slayer, Firefly, Angel, and Agents of S.H.I.E.L.D. He wrote and directed Marvel Cinematic Universe films The Avengers and The Avengers: Age of Ultron. He is also known for his internet series Dr. Horrible's Sing-Along Blog.