Flabber
Flabber is a phantasm who was trapped inside a pipe organ, and was freed by the kids when they played three notes on the organ. He proves to be friendly, and out of gratitude for releasing him, he offered to grant them one wish. They wished to become their comic book heroes, the Big Bad Beetleborgs. Although his magic doesn't always work the way they hoped it would, he acts as an advisor and best friend, he offers needed magic to the kids when fighting the Magnvavores. He is the head of the Hillhurst Mansion and is usually the one to keep the house monsters in check.
Count Fangula
Count Fangula is a vampire, a not so good one, at least he is friendly. He is the only one that can understand Wolfie and translate for him.
Frankenbeans "Frankie"
Called "Frankie" for short, he is a strange, lumbering Frankenstein-type monster. He was once kidnapped by the Magnavores, and held by ransom in exchange for the Beetleborgs' Beetle Bonders. Dr. Baron von Frankenbeans, his creator, later showed up and had various visits.
Mums
Mums is a 5,000 year-old Egyptian mummy, but he can unwrap his bandages to reveal a different form under his bandages. He has 703 brothers and sisters. Two archaeologists came to return Mums to the crypt in which they found him in order to get rid of a curse placed on them.
Wolfgang "Wolfie" Smith
Wolfie is a werewolf and is treated more like a family dog than a monster at Hillhurst. Only Fangula can translate what Wolfie is saying most of the time. Probably the bravest and most cunning of the Hillhurst Monsters because he's the only one of the group who has tangled with the bad guys at least once.
The Flabbettes/The Pipettes
A multicolor sprite-like trio of ladies who live in the pipe organ. They act as Flabber's back-up singers.
Ghoulum
A living stone statue type monster that resides in Hillhurst Mansion who often had little to say or do other than what statues do best, stand in place. While not the most active monster of Hillhurst Mansion on rare occasions, he would join in on the other monsters' mischief. One time, he was accidentally exposed to a potion that made him evil and caused him to grow into a giant under Noxic's control.