Metalocalypse: The Doomstar Requiem – A Klok Opera is a rock opera special for the Adult Swim animated series Metalocalypse. It was announced on May 10, 2013, by Adult Swim and was released on October 27, 2013. The special picks up directly after Metalocalypse season 4. It featured all-new music from Dethklok, which was released on a soundtrack album on October 29, 2013.

Brendon Small is an American actor, stand-up comedian, writer, director, producer, and musician who is known for co-creating the animated series Home Movies and Metalocalypse. He also writes the music, and is the main performer for the virtual melodic death metal band Dethklok, which began as the subject of Metalocalypse but has taken on a life of its own, with four albums and an occasional live touring band, headed by Small. Small has also released two albums under his own name, in a similar musical style to Dethklok.