Mutant Enemy Productions' three-part web series, Dr. Horrible's Sing-Along Blog, is now 10 years old. Created by Joss Whedon, Jed Whedon, Zack Whedon, and Maurissa Tancharoen, the musical comedy stars Neil Patrick Harris, Nathan Fillion, Felicia Day, and Simon Helberg. The series follows Dr. Horrible (Patrick Harris), an evil genius who is determined to win the love of Penny (Day), but is constantly thwarted by hero Captain Hammer (Fillion). With a catchy soundtrack and infinitely clever dialogue and scenarios, Dr. Horrible's Sing-Along Blog is an all-around favorite.