Dr. Horrible's Sing-Along Blog is a web-only, three-part musical mini-series created and written by Joss Whedon, along with his brothers Zack and Jed, and Maurissa Tancharoen.

The show follows the story of Dr. Horrible, a wannabe villain who dreams of joining the Evil League of Evil, and his attempts to impress his crush, Penny, while dealing with his nemesis, Captain Hammer.