The fourth and final season of the animated show Metalocalypse originally aired on Adult Swim from April 29 to July 15, 2012 with 12 episodes.

This season featured several new guest stars, including Drew Pinsky, Amber Tamblyn, Werner Herzog, Byron Minns, Christopher McCulloch, Samantha Eggar, Pat Healy, Ben Shepherd and Kim Thayil of Soundgarden, Cam Pipes of 3 Inches of Blood, Jon Hamm, Janeane Garofalo, Patton Oswalt, Marc Maron, Dweezil Zappa, Asesino, James Urbaniak, Chris Elliott, and Billy Gibbons of ZZ Top, as well as returning guest stars, like Laraine Newman, George "Corpsegrinder" Fisher of Cannibal Corpse, Frankie Ingrassia, and Andy Richter.

Guest Voices: Drew Pinsky, Amber Tamblyn & Werner Herzog At a press conference discussing their new album, the band do nothing but fool around, and Nathan constantly quips his new catchphrase, "That's doable."

Meanwhile, Toki has become resentful of the band due to his constant exclusion, and resolves to start his own club, which Murderface is not invited to join because of his mustache, which he has grown out of control.

The band prepares to open their new urban youth center to alleviate the accusations of racism, and Toki gives them secret uniforms for his club, along with special hats.

They attempt to get revenge by using his credit card to purchase plastic explosives, believing it will get him in trouble, instead they are beaten and apprehended by authorities (along with Murderface).

After the credits, Pickles is gloating to his mother about his "blue-collar" success, but she proceeds to instantly belittle his accomplishments, saying that it is more important to play in Dethklok and rebuild the economy.

After a week, due to them not bringing any food, money, or identification they are taken to a palace where a sultan tells them that they are to become new members of his harem and must immediately perform fellatio on him.

As Jamawa, his financial advisor, and his army are killed, they are saved by a group of female mercenaries disguised as wives in the sultan's harem.

Guest Voices: Jon Hamm, Janeane Garofalo, Frankie Ingrassia & Werner Herzog Offdensen goes out of town and leaves Nathan and Pickles in charge as Toki goes to Rock-A-Rooni Fantasy Camp where he tries to make friends with other campers.

Guest Voices: Patton Oswalt, Werner Herzog, Marc Maron, Dweezil Zappa, and Kim Thayil of Soundgarden Murderface receives an award for being the "brutalest looking" musician in the world.

Angered, he attempts to better his appearance through cosmetic surgery, but finds he lacks the funds to pay for the procedure when Offdensen reminds him that he had recently lost most of his money in a lawsuit.

At the awards ceremony, the rest of the band show up with a plethora of quick, albeit sloppy and ineffective, cosmetic treatments while Murderface returns wearing a full-face helmet.

The band splash coffee and squirt lemon juice in Murderface's eyes and the audience flees in horror as the credits roll.

The band prepare to go back into the water via DethSub to record the new album and are informed by Offdensen that women are not allowed on board (security risk) with the exception of Abigail.

Pickles attempts to kiss Abigail but is turned down, he calls out her sexual frustration and she reveals that she uses a vibrator as a substitute for having sex with co-workers.

To move on, Nathan and Skwisgaar team up with Dick Knubbler to search for a new sound, Murderface decides to run for Congress from New Jersey with Toki as his intern, and Pickles retires from music to open a winery for the world's most alcoholic wine.

Each of these ventures fail (Nathan and Skwisgaar cannot find a better sound than Dethklok, Toki accidentally releases pictures of Murderface masturbating, and Pickles's wine causes illness due to steroids in the grapes), and the group sullenly heads for Iceland to play their last show.

At the concert, while Nathan and Pickles struggle with both performing and considering apologizing to each other, Mr. Salacia attacks, slaughtering the fans with his powers before killing Roy Cornickelson.

The whale seen in several season four episodes is revealed to be a prophet that speaks to Nathan in his dreams, and it drove him to destroy the album in "Prankklok" because it was the wrong message.

Later, at Roy Cornickelson's funeral, Nathan gives the eulogy in front of a huge crowd - including Abigail and Magnus Hammersmith, who Toki brought despite warnings from Dr. Rockzo - and ultimately becomes overwhelmed by the emotions surrounding the collapse of Dethklok.

Nathan apologizes to Pickles for everything and they embrace, but a hidden bomb is suddenly detonated, opening up fissures in the ground from which the Metal Masked Assassin and the Revengencers emerge.

However, when he is knocked down by one of Offdensen's punches, the Metal Masked Assassin yells an order to Magnus, who stabs Toki after proclaiming the arrival of his revenge, incapacitating him.

Evacuating to the submarine once more, Offdensen tells the remaining members of Dethklok that they must complete the album's final song and release it to have any hope of stopping the Metalocalypse, but in order to do that, they must find and save Toki and Abigail, whom he and Ishnifus believe are still alive somewhere.