Dr. Sidney Hieronymus Algernon Zitbag
Voiced by: Christian Rodksa
A Mad Scientist who moves into a castle and starts his own pet shop where he specializes in monster pets.
- Catchphrase: He often exclaims "Great galloping globules" or some variation thereof.
- Jerk with a Heart of Gold: Depending on the Writer. He's invariably shown to be unscrupulous and shifty, but he usually does care about his canine companion Horrifido and the Exorsisters.
- Mad Scientist: He's a mad scientist who often creates new monster pets for his pet shop.
- Really 700 Years Old: On occasion, it's brought up that he's actually hundreds of years old.
- Twin Threesome Fantasy: He loves both of the Exorsisters and isn't exactly content with pursuing a relationship with just one of them.
Horrifido
Voiced by: Max Andre
Dr. Zitbag's loyal skeletal canine companion. He was originally the ghost of Fido, the pet dog of the castle's previous owner Charles de Ghoul. After Zitbag unintentionally reunited his spirit with his bones, he became the doctor's assistant in running the pet shop.
- Dem Bones: He's a skeleton dog.
- Dogs Are Dumb: Averted. If anything, he's more intelligent than Zitbag.
- Hypercompetent Sidekick: He's Zitbag's assistant and often proves to be more rational and level-headed than his boss.
- Meaningful Rename: He was originally named Fido, but happily accepted the name Horrifido when Zitbag said that that name would be scarier.
- Real Men Wear Pink: He wears a pink bow around his neck.
- Servile Snarker: He's not afraid to make snide remarks at Zitbag's expense.
- Undying Loyalty: In spite of his boss frequently abusing him and taking him for granted, Horrifido never leaves him.
Zombunny
A silent and immobile zombie rabbit who is often seen hanging around the Transylvania Pet Shop.
- Empty Shell: He's a zombie who doesn't talk and rarely moves.
- Interspecies Adoption: Is briefly taken in by a family of yetis in "Pinball Wizard".
- Running Gag: The fact that he accomplishes whatever he's put up to by doing nothing.
- The Speechless: He never speaks, which may have something to do with the fact that he's an undead cadaver.
The Exorsisters
Voiced by: Nicolette McKenzie
Twin vampire sisters and Dr. Zitbag's neighbors. Zitbag falls in love with them and does everything he can to win their affection. Their individual names are Sinista and Bimbella.
- Daywalking Vampire: In spite of being vampires, sunlight does not harm them.
- Identical Twin ID Tag: To tell them apart, Sinista's hair streaks and eyelids are colored purple while Bimbella's are colored white. The later episodes also depict Sinsita as having messier hair.
- Impossible Hourglass Figure: They have large breasts, wide hips and incredibly thin waists.
- Long Pants: Under their dresses they have purple tentacles that closely resemble the bottoms of their dresses. The point where their upper bodies end and their tentacles begin is always hidden.
- Polar Opposite Twins: Sinista is the grumpier of the pair, while Bimbella is more kindhearted.
Officer Deadbeat
Voiced by: Kerry Shale
A demonic-looking police officer who wants Dr. Zitbag out of the castle so he can make it his new police headquarters. He'll stoop to any low to make Zitbag forced to leave the place.
- Dirty Cop: He'll try any underhanded tactic to make Zitbag close down his pet shop.
- Good Is Not Nice: He's a police officer, but not only is he willing to stoop to underhanded methods to make Zitbag shut down his pet shop, he'll also often antagonize Zitbag just for kicks.
- Henpecked Husband: He's frequently implied to be intimidated by his seldom-seen wife.
- Laser-Guided Karma: Whenever he tries to get Zitbag's pet shop shut down using underhanded methods, he's likely to get his just deserts for it in the end.
- Losing Your Head: He has no neck, so his head is always floating above his shoulders. On some occasions, his head gets separated from his body.
- Meaningful Name: In French, his name "Sanglote" (which means "sniffling") can also be read as "Sans glotte" ("no glottis"), which is perfectly appropriate since he in fact does not have a neck.
- Strong Family Resemblance: His son Damian doesn't look much like him initially, but the family resemblance is blatant in "Son of Zitbag" and "I Was a Teenage Zitbag".
Professor Sherman Vermin
Voiced by: ???
A rival mad scientist who tries to outdo Zitbag in courting the Exorsisters and selling monster pets.
- Evil Redhead: He has red hair and he makes Zitbag look like a saint.
- Mad Scientist: Like his rival, he's an insane scientist who does unorthodox experiments.
- The Rival: He's Dr. Zitbag's main competition.
- Why Did It Have to Be Snakes?: He's deathly afraid of insects and arachnids.
Fingers Malone
Voiced by: ???
A criminal in Transylvania whom Zitbag has run afoul of on more than one occasion.
- Bald of Evil: He's a bald criminal, though he looks more like he has a shaved head in the later episodes.
- Dumb Muscle: His later appearances portray him as Professor Vermin's dim-witted thug.
- Took a Level in Dumbass: When he first appeared in "Grime Doesn't Pay", he was a crafty and manipulative thief. When he started working for Professor Sherman Vermin, he was reduced to being a simpleton.
