Douglas Petrie is an American screenwriter, director, and producer. Best known as a writer, director, and co-executive producer on Buffy the Vampire Slayer. He co-wrote the screenplays for the Fantastic Four film and Harriet the Spy. He has also written for the television shows Angel, The 4400 and Tru Calling. He served as a co-executive producer and writer for two seasons on CSI: Crime Scene Investigation and as a consulting producer and writer on the second season of Pushing Daisies. He made a cameo on Joss Whedon's web-based film, Dr. Horrible's Sing-Along Blog, as "Professor Normal".