The Monster Hunters are an ancient organization determined to capture and, to an extent, kill Monsters. They were started in medieval Britain by an unknown man. They sought to capture Monsters and use them as slaves. They used magical weapons to tame Monsters. After Monsters began emigrating to America, their activity seemed to slow down. Many years after the establishment of Monster High, they began targeting the prestigous institution. They began using futuristic weapons that proved more effective on the Monsters. They fealt Monster High was a center for Monsters and that if they destroyed it, the Monsters would go into hiding and less of an "annoyance". Despite this they had a few Monsters as members who fealt they were a superior kind of Monster.
- Dr. Van Helscream- He was the leader of the Hunters for many years. He masqueraded as a Monster-Normie realtionship advisor. He was later unmasked as an evil mastermind who wanted to destroy Monsters and use them for many purposes. He died after slipping into a chasm created by Lord Monsutakingu.
- Ms. Crabgrass- A spy for the hunters stationed at Monster High. She was unmasked as a traitor after Helscream arrived and was unmasked as well. She was absorbed into a chasm at the Monster Corps base after attempting to control many members.
- The Masked Lantern- A robot who was originally a disquise of Axel Venator. After his plan was thwarted by Gina Djinn, he was absorbed by a lantern and turned into a symbiotic robot that only served Helscream. He was destroyed by Gina Djinn during the major invasion of Monster High.
- Gillian Sprites- A witch with strong mental issues. She resembles a fairy princess and has a high magical power. She disquised herself as Jill Haggs to infiltrate Monster High. Her identity was revealed by her ex-boyfriend Axel Venator. She erased his memory and went unknown again. Her identity was later revealed and her history with her sister, told. She later died from a magical backfire in a duel between her and Wicca.
- Master Orc- A mindless monster used only during major attacks. He was destroyed by Gary Goyles when he went on a rampage due to thee death of Dracilia.
- Dracilia- A vengeful dragon who can change her form into a human-shaped body. She has a past with Helscream and feels he owes her for saving his life after being absorbed into a lantern because of his second invasion. She morphed into a dragon to fight in the major invasion of Monster High. She was killed by Nefera de Nile because she caused a large tower to fall on her.
- Valentine Wingbeat- A narcisistic Vampire who was originally a student at an unnamed Vampire school but temporarily transferred to Monster High. He later joined the Monster Hunters under Ms. Crabgrass and acted as a spy in the Monster Corps. He was absorbed into a chasm with his allies.
- Ettie Bominable- A charming yeti. He was a member of the Monster Corps but later became a traitor and joined the Monster Hunters. When a traitor was believed to be in the Corps, it was originally thought to be Thornhilda McFlytrap. He was revealed when the main attack began. He was absorbed into a chasm along with his allies.
- Axel Venator- He was a top member, being the leader's son. He betrayed them after his invasion as The Masked Lantern. He later supplied Monster High with with weapons during the later invasions.
- Jill Haggs- An alternate form of Gillian Sprites. She infiltrated Monster High and befriended many students. After Gillian was released the two entities split into two seperate people.Jill returned to Monster High as a regular student.
- Ranny Wraith- A young wraith who became a student at Monster High to spy on students. He fell for Rochelle Goyle and she fell for him but she never admitted it. He later turns sides after seeing the Hunters hurt Rochelle. He freed the 13 captives leading to the Hunter's defeat. He joined the Monster Corps and fought the traitor with his teammates.
- JackBots- Pumpkin-headed robots who serve The Masked Lantern.
- Pixies- A floating cloak with a mask and weilds two large blades with monsterous hands under their cloak. Led by Gillian Sprites.
- Orcs- Mindless mutants that have brute strength and a powerful laser. They are led by Master Orc.
- Wyverns- Serpent-like dragons that move very swiftly. They are led by Dracilia.
- CirrusMen- Brutes made from a cloud-like substance. They orginally appeared as floating heads but can transform into large men to attack others. Led by Valentine Wingbeat.