Dr. Horrible's Sing-Along Blog is an online mini-series from director Joss Whedon. The show is a musical tale about a villain played by Neil Patrick Harris.

In 2009, "Horrible" won an Emmy for "Most Outstanding Special Class Short Format Live Action Entertainment Program." Horrible also made an appearance at the 2009 Emmy Awards, which was hosted by Harris.

• Neil Patrick Harris as Dr. Horrible
• Nathan Fillion as Captain Hammer
• Felicia Day as Penny

Act I is a 14 minute segment that introduces several characters. The segment begins with super-villain Dr. Horrible practicing his evil laugh. He mentions that he disapproves of the system, stating that "the world is a mess" and that he wishes to "change the world" by "ruling" it.Dr. Horrible Sing-Along Blog: Act I

He loves a "fellow laundry person," Penny, but can't build up the courage to talk to her. During a heist attempt, Penny approaches him about signing a petition. She distracts him from the heist and his enemy Captain Hammer intervenes, carelessly risks Penny's life and then saves her by pushing her into a pile of garbage. Dr. Horrible finishes the heist while the two are talking.Dr. Horrible Sing-Along Blog: Act I

Act II is a 13 minute segment that begins with Dr. Horrible singing from his loss of Penny to Captain Hammer. After the song, Captain Hammer and the L.A.P.D. are viewers of Horrible's video blog and discover Horrible's only way into the Evil League of Evil is to murder someone. While trying to decide who it should be, Horrible visits the laundromat and encounters Penny. Horrible and Penny spend some time together and then Hammer shows up. Hammer quietly tells Horrible that he's going to date Penny to hurt him. With this threat, Horrible decides who he will murder.Dr. Horrible: Act Two

Joss Whedon conceived the idea of a super-villain musical during the 2007 - 2008 writers strike. In order to circumvent the restrictions of the strike, Dr. Horrible's Sing-Along Blog was written for initial distribution on the Internet. Whedon partnered with "everyone I had worked with, was related to or had ever met,"Dr. Horrible.com: Master Plan including Felicia Day (Buffy the Vampire Slayer) and Nathan Fillion (Firefly.)Times Online: Web Watcher: Dr. Horrible's Sing-Along Blog (July 16, 2008)

Dr. Horrible's Sing-Along Blog is available to view for free from its debut on July 15, 2008 through midnight on July 20, 2008. After that date, the mini-series was removed from distribution, and the series is now available on DVD.

On the launch of Act One of the series on July 15, 2008, the official site hosting the show crashed. The following message was found on the site:

• "We love you for crashing the site, we really do. In the meantime, those of you who have iTunes capabilities can go there and get your fix. Our site should be up and running again in a few hours. Your support is warming our hearts and kicking our asses. So thank you thank you." J, M, J, Z [writers and exec producers Joss Whedon, Maurissa Tancharoen, Jed Whedon & Zack Whedon]E! Online: Dr. Horriblee Site Crashes (July 15, 2008)

"It is time for us to change the face of Show Business as we know it. You know the old adage, 'It's Show Business — not Show Friends?' Well now it's Show Friends. We did that. To Show Business. To show Show Business we mean business. (Also, there are now other businesses like it.)"—Joss WhedonDr. Horrible.com: Master Plan

"More talented writers of prose and music cannot be found. I can't stop singing these songs, even the ones I'm not in."—Felicia DayThe Flog: Yes, I am in Dr. Horrible's Sing-Along Blog (March 17, 2008)