Neil Patrick Harris and Nathan Fillion in Dr. Horrible's Sing-Along Blog (2008)

Nathan Fillion in Dr. Horrible's Sing-Along Blog (2008)

Neil Patrick Harris in Dr. Horrible's Sing-Along Blog (2008)

Neil Patrick Harris, Nathan Fillion, and Felicia Day in Dr. Horrible's Sing-Along Blog (2008)

Felicia Day at an event for Dr. Horrible's Sing-Along Blog (2008)

Nathan Fillion at an event for Dr. Horrible's Sing-Along Blog (2008)

Joss Whedon at an event for Dr. Horrible's Sing-Along Blog (2008)

Nathan Fillion, Joss Whedon, and Felicia Day at an event for Dr. Horrible's Sing-Along Blog (2008)

Nathan Fillion and Felicia Day at an event for Dr. Horrible's Sing-Along Blog (2008)

Neil Patrick Harris, Nathan Fillion, Joss Whedon, and Felicia Day at an event for Dr. Horrible's Sing-Along Blog (2008)

David Fury in Dr. Horrible's Sing-Along Blog (2008)

Neil Patrick Harris, Nathan Fillion, and Felicia Day at an event for Dr. Horrible's Sing-Along Blog (2008)

Neil Patrick Harris, Nathan Fillion, Simon Helberg, and Felicia Day in Dr. Horrible's Sing-Along Blog (2008)