Facebones. Normally, just a mildly goofy and gory mascot/caricature Dethklok uses to make their informational videos, right? Well...it is until you see the Mordhaus Tours reel on the Season 1 DVD Extras. When he takes you down to the secret basement hallway where the Jomfru brothers were, uh..."dealt with", he starts up laughing. Maniacally. Made all the more creepy by the fan theory that Offdensen/Charles is the one who does the in-universe voice for Facebones, possibly as an outlet for the frustrations of his job.
While the OTT-ness of most Metalocalypse's violence does make it more funny than terrifying, the part in the second episode of the second season where the prisoner from Die-For-Dethklok.com uses half of his dead brother's face as a mask for a teenager was not... pleasant.
Most find the humor in or ignore pretty much all the gore...except for that complete freak-out scene in "Snakes and Barrels". It's fine right up until the part with a thousand angry aborted babies.
And in the ending of the follow-up, which includes said aborted babies returning to wreak havoc on the audience, cute bunnies transforming into huge, man-eating bunny monsters, the otherwise cute and nice Toki Wartooth beating another concert goer to death in an extremely scary manner, and to top it off, the recently rehabilitated Dr. Rockso appearing on stage, absolutely high and announcing his comeback in a very scary manner.
Dr. Rockso: I'm b-b-b-b-b-back, baby! The name's Doctor Rockso, the rock n' roll clown! And I do cocaine!
The ending of "Dethfashion" is probably the most disturbing scene in the series. At least there was something of a laugh when Nathan says "Oh God...you're fired by the way."
The episode "Dethealth" contains a scene where the band members decide to drink bleach in order to falsify the results of a urine test. The Nightmare Fuel comes into play when Nathan has a hallucinatory episode featuring a beautiful yet inhuman woman who exchanges kisses with him. After she pulls back her face morphs into a horrific visage complete with rotting teeth and a skeletal nose. Nathan's face then begins to rot in a likewise manner ending with his gangrenous lower jaw falling into the water below. This description doesn't even begin to do justice to how unnerving this scene is. Nathan is probably not the only one screaming...
There are reports of viewers dry heaving at the sight of Murderface drinking that bleach.
The start of they episode where they neuter animals via a machine. There was just something disturbing about seeing people cheering around animals getting their jewels cut off.
Mr. Salacia in general.
At the end of season one, he decapitates Crozier's troops with bass music and then dismembers Ravenwood.