Lord Moldy Butt is a character spoof of Lord Voldemort from the Harry Potter series. He was portrayed in two episodes, "Nigel Planter and the Chamber Pot of Secrets" and "Nigel Planter and the Order of the Peanuts". He is voiced by John Kassir.
He is skinny, often seen wearing a black coloured bodysuit and having a green head which is similar to Voldemort's.
In the first mentioned episode "Nigel Planter and the Chamber Pot of Secrets", he is believed to be out to kill Nigel Planter (spoof of Harry Potter,) and thus Grim, Billy and Mandy have been assigned to protect the boy, although Moldy Butt had still managed to encounter and torment Nigel many times throughout the episode, warning him to stay away from "The Chamberpot of Secrets" at each time. Mandy discovers the Chamberpot which contained a Moldy Butt costume and they all discover it was Dean Toadblatt (who was first seen in Toadblatt's school of Sorcery) who was pretending to be Lord Moldy Butt in order to scare Nigel into leaving the school. The actual Lord Moldy Butt makes a cameo appearance at the end of the episode in the center of the Earth on a ledge with a pot.
In "Nigel Planter and the Order of the Peanuts," The true Moldy Butt is revealed to be a real estate agent who had been trying to track Nigel down in order inform him of his heirship of his family peanut company, and enlists Grim, Billy and Mandy to help him.
- As a running gag, something breaks whenever someone speaks his name, which is why most characters address him as "he-who-should-not-ever-be-named," respectively parodying both the phobia of Voldemort's name amongst the magical community of Harry Potter and the title with which they use to address him; "He-Who-Must-Not-Be-Named".
- His name was originally "Lord Moldy Wart".
- "Lord Moldy Wart" is a name that was later used when Fairly Odd Parents spoofed Harry Potter in Wishlogy Part 1.