claim: Doug Petrie made a cameo in Dr. Horrible's Sing-Along Blog as "Professor Normal".
evidence: Douglas `` Doug '' Petrie is an American screenwriter , director , and producer .. producer. Television producer. director. Television director. screenwriter. screenwriter. Best known as a writer , director , and co-executive producer on Buffy the Vampire Slayer .. producer. Television producer. director. Television director. Buffy the Vampire Slayer. Buffy the Vampire Slayer. He co-wrote the screenplays for the Fantastic Four film and Harriet the Spy .. Fantastic Four. Fantastic Four ( 2005 film ). Harriet the Spy. Harriet the Spy ( film ). He has also written for the television shows Angel , The 4400 , Tru Calling and American Horror Story  : Coven .. Angel. Angel ( 1999 TV series ). The 4400. The 4400. Tru Calling. 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 .. producer. Television producer. Pushing Daisies. Pushing Daisies. second season. Daredevil ( season 2 ). He made a cameo on Joss Whedon 's web-based film , Dr. Horrible 's Sing-Along Blog , as `` Professor Normal '' .. Joss Whedon. Joss Whedon. He served as co-executive producer on the first season of the Netflix show Daredevil , and took over as showrunner for its second season alongside Marco Ramirez .. producer. Television producer. first season. Daredevil ( season 1 ). Netflix. Netflix. Daredevil. Daredevil ( TV series ). showrunner. showrunner. second season. Daredevil ( season 2 ). In April 2016 Petrie and Ramirez were announced as showrunners of The Defenders , a miniseries that crosses over Daredevil , Jessica Jones , Luke Cage , and Iron Fist .. Daredevil. Daredevil ( TV series ). The Defenders. The Defenders ( miniseries ). crosses over. crossover in fiction. Jessica Jones. Jessica Jones ( TV series ). Luke Cage. Luke Cage ( TV series ). Iron Fist. Iron Fist ( TV series )