Cover of Cover of Supervillain!.
Supervillain!, sub-titled An Unofficial And Unauthorised Guide To The World Of Dr. Horrible's Sing-Along Blog, was published on April 28, 2018 and written by David Black. The book serves as an episode guide to Dr. Horrible's Sing-Along Blog, the Emmy Awards interruption and comics published by Dark Horse.
References[]
https://www.amazon.co.uk/Supervillain-Unofficial-Unauthorised-Sing-Long/dp/1980904820/