Many of the characters possess pets that have some connection to their nature, personality and/or family history. Generally the pets stay home while their owners are at school, although Lagoona Blue's pet and Operetta's pet accompany them at school.
|Watzit is Frankie Stein's pet simulacrum. Like his mistress, he has been stitched together, in his case from the best parts of several other house pets. Watzit takes mostly after his dog components.|
|Count Fabulous is Draculaura's pet bat. He has a fondness for insects, which is a good thing considering Draculaura's vegetable garden attracts hundreds of them. He usually wears a pink heart dress and bow to please Draculaura.|
|Crescent is Clawdeen Wolf's fuzzy little kitten. Like Clawdeen, Crescent has an alpha attitude and usually goes her own way, but she is also loyal to those important in her life.|
Lagoona Blue's pet piranha is normally quite friendly despite her species. Lagoona carries her around in a special fishbowl purse.
A cute little cobra with a not-so-cute bite. Hissette was an accidental stowaway in a gift from Egypt to Cleo de Nile and was swiftly adopted by the princess. She is normally dressed in gold bangles.
Sir Hoots A Lot
Ghoulia Yelps's powder blue owl. He is very smart but sometimes stubborn.
Holt Hyde's pet is a yellow and orange chameleon. He seems to enjoy music and accompanies his owner on night time strolls when they first move and get to know the place. Being the same person, Jackson Jekyll also owns Crossfade, but when with him Crossfade is green and yellow.
A two-tailed black and orange rat owned by Deuce Gorgon. Deuce's mother was never pleased that her son named him after her enemy, and she once threatened to turn the rat into a paperweight if he kept raiding the kitchen for cheese.
A cheeky ghost ferret owned by Spectra Vondergeist.
A rough gargoyle bulldog owned by Clawd Wolf.
Abbey Bominable's pet wooly mammoth, she is very tough.
Nefera de Nile's pet scarab beetle, which she thinks is a source of good luck.
Toralei Stripe's pet sabre-tooth tiger cub, it is quite tough and can go through a ball of dragon thread a day.
Memphis "Daddy O" Longlegs
Operetta's pet spider. So far he's the only official pet of a Monster High student to actually make an appearance in the webisodes.
Cushion is Howleen's pet hedgehog with a mowhawk.
Roux is a gargoyle griffin owned by Rochelle Goyle, it is protective of its owner.
Chewlian is a hungry venus flytrap owned by Venus McFlytrap.
Captain Penny is a robotic penguin owned by Robecca Steam
Nati is a butterfly owned by Skelita Calaveras
Qing is a qilin owned by Jinafire Long
Smokey is Deuce Gorgon's pet dragon from when he was a little boy. Smokey was the first pet he had. While playing one day, Deuce accidentally petrified Smokey and because he had little control over his powers back then, the spell didn't wane after 24 hours. Smokey has been a statue for many years while Deuce waits, heart-broken but patient, until the day he can be reunited with Smokey.
Nightmare is the fire-breathing horse of Headless Headmistress Bloodgood, functioning both as a pet and an assistant. Nightmare is a neurotic wreck of a horse, but intensely loyal to her owner and appreciative of kind gestures.
The frogs are Lagoona Blue's pets at school since the day she saved them from dissection. Their numbers are legion and they eagerly help Lagoona whenever she asks them for it. Sofar they are the only additional pets to be made as a figurine in a doll set.
Aside from Neptuna Lagoona also has an entire school of piranhas it is unknown if the piranhas in the school's pool are also her or the other swim team members'.
Bones is the name of the skeletal dog of The Calaveras household.
- On October 6, 2010, the student that hosts the Monster High Facebook account asked the visitors what kind of pet she should pick now that her parents finally allowed her to have one. The visitors could choose between a striped owl, a white hamster, or a pink mini-dragon. As revealed on October 20, 2010, the pink mini-dragon won the vote. The Facebook host referred to her pet as a 'he'.
- C.A. Cupid is known not to have a pet.
- Purrsephone and Meowlody previously had a pet canary, but one of them became allergic and so they had to part with him.
- Invisi Billy used to have a dog, but he had to give him away because he couldn't walk him without people thinking the dog was a stray. Nowadays, Invisi Billy has a box which may or may not contain a cat.