A look at the story behind Marvel Studios and the Marvel Cinematic Universe, featuring interviews and behind-the-scenes footage from all of the Marvel films, the Marvel One-Shots and "Marvel's Agents of S.H.I.E.L.D."

Dr. Horrible's Sing-Along Blog is a 42-minute tragicomic musical in three acts, each released separately. It tells the story of Dr. Horrible, an aspiring supervillain, Captain Hammer, his superhero nemesis, and Penny, their mutual love interest. The movie was written by writer/director Joss Whedon, his brothers Zack Whedon and Jed Whedon, and Jed's then fiancée, actress Maurissa Tancharoen. The writing team penned the musical during the WGA strike. The idea was to create something small and inexpensive, yet professionally done, in a way that would circumvent the issues that were being protested during the strike.