Aldermach Maggotbone (voiced by Larry Murphy) is the Devil, the leader of Hell. He is Callie's father. He used to be the chief prosecutor in Hell's court, probably for 2,000 years, and would like Callie to work there, too. He is known as "Skinny Bob" before he succeeded as the leader of Hell 35 years ago, as told in episode "Ride Me to Hell".
He runs his own soul trading business, Maggotbone Soul Industries. Its stock has been tumbling in the episode "Wail Street". After the event of acquiring Mark Lilly's supposedly massive soul, which turns out to be the size of a pea, the stock plummets to a new low.
Aldermach marries a new wife each year, usually letting his new wife bury the old one. In fact, in the first season there have already been three females that the Devil has been together with for some time, including Callie's human mother Rosie.
Aldermach has a strong dislike for Mark Lilly, Callie's human boyfriend. He would rather have her be together with Twayne Boneraper. This is due to the magical blood pact with the Bonerapers that he took after he ditched Twayne's mother Violet at the altar.
- Aldermach is an avid fan of football, specifically the New York Jets.
- Aldermach is a heavy drinker, leading him to believe that his office is a bar in "Wail Street".
- The source of Aldermach's great size (and in fact the girth of all demons holding the title of "Devil") is the demon snake Slitherax (a monstrosity consisting of many eyes and mouths), which he swallowed during the ceremony naming him the Devil. In the episode "Ride Me to Hell", Aldermach disgorges the snake and returns to his original, smaller size.
- Name may possibly a reference to Adramelech who is a pagan god/demon
- Sympathy for the Devil
- Hell for the Holidays
- Soul Sucker
- Wet Hot Demonic Summer
- Callie and Her Sister
- Ride Me to Hell
- Attack of Mark's Clone
- Wail Street