I am the one, who's creating the monsters.

Listed below on the page is a List of Monsters, either created by Seth Harper or Principal Grey.


A monster is a creature created to destroy Mech-X4 and the team, but it's especially created to destroy Ryan Walker, the pilot of the robot. Monsters have been featured in every episode since the first, and they will continue to do so in Season 2.




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  • Clawboon was made out of Crab and Baboon DNA.
  • In Let's Open The Monster Heart!, Davage planted the Primorphous Core to one of the checkpoints where Primorphous Gel was.
    • Clawboon was specifically made to get the pilots of Mech-X4.
    • Clawboon was too powerful which made Mech-X4 retreat.
  • In Let's Get the Big Bad!, Clawboon helped Seth (as the Mastermind) escape from Mech-X4 so they don't know his identity.
    • Clawboon was destroyed by the X-Weapon.
  • Principal Grey could turn into Clawboon whenever she wants because the ooze was zapped by the X-Weapon.
Wasp Meleon

Chameleo Wasp

  • Chameleo-Wasp was made out of Wasp and Chameleon DNA.
  • Seth was able to control Chameleo-Wasp with his mind.
  • Chameleo-Wasp could turn invisible when it wants.
  • In Let's Destroy Some Ooze!, Seth fought Mech-X4 by using the monster.
    • Seth pretended the monster was wounded so when Mech-X4 shot the Arm Cannon, it would look like they destroyed Bay City High.
    • Chameleo-Wasp flew away from Mech-X4.
  • In Versus The New Evil, the Mech-X4 team found Chameleo-Wasp.
    • It was revealed in Unlocking the MECH that after they destroyed Seth's monster, they almost destroyed Chameleo-Wasp.
    • Chameleo-Wasp was defeated by the Cold Cannon.
Unnamed Monster (1)

Unnamed Monster (1)

  • The monster was not controlled by a Primorphous Core, it was controlled by Seth's brain.
  • Seth fought Mech-X4 whilst inside the monster.
  • According to Cassie, it is the biggest monster Mech-X4 have faced.
  • In Let's End This! Part One, Seth surprised the team when Ryan heard Seth's voice in the monster.
  • In Let's End This! Part Two, the monster got hit by the X-Weapon but it survived.
    • Seth was waiting for Grace to come in the monster.
    • The monster could have almost defeated Mech-X4 if they didn't leave.
    • When Ryan was going to get the Primorphous Core missile, Seth got into his monster to get it first.
      • Ryan got the Primorphous Core missile before Seth and Ryan threw the missile back at Seth.
        • Seth evacuated by ejecting out of the monster.


  • Grey made a monster with the ooze she took in Versus The New Evil.
  • Insectashark is the first and only monster that could swim underwater.
  • In Versus The Deep, Ryan got a vision about Insectashark from Seth.
  • Insectashark was found by Mech-X4.
    • Mech-X4 drilled through Insectashark which turned it into ooze.


  • Grey made Arachno-Rhino by using the ooze she took in Versus The New Evil.
  • Arachno-Rhino was not named by Spyder, but by Seth.
  • In Versus Harper's Ghost, Grey used the monster to attack the Mech-X4 team and Seth Harper.
    • The Mech-X4 team used the X-Weapon to destroy Arachno-Rhino and before it could charge at Mech-X4.
Unnamed Monster (2)

Unnamed Monster (2)

  • This was another monster Grey used using the ooze in Versus The New Evil
  • The monster could suck energy with its stinger.
  • In Versus The Dark Night, the monster sucked power off the Power Plant and gave it to the secret warehouse Grey was in.
  • Grey used the energy it collected to store inside Traeger
  • Ryan and Mark noticed that the monster was going to strike at Veracity's house next.
  • Ryan and Mark got into Mech-X4 to defeat the monster.
    • The monster took power off Mech-X4 and took it to Grey.
  • It's unknown where the monster went after it released its energy.

Humans With Monster DNA




  • In Let's Call It MECH-X4!, Harris accidentally drank some ooze which made him turn into a monster.
  • In Let's Get Some Air!, Harris couldn't control when he turned into a monster.
    • The team made an antidote which turned him back to normal.
  • In Let's End This! Part One, Harris drank some ooze he found at Harper Futuristics.
    • He fought off Morris and Seth's henchmen.
    • To turn him back to normal, Harris drank the same antidote he used before.

Grace Walker

  • In Let's End This! Part One, Seth put monster DNA inside Grace's brain.
  • In Let's End This! Part Two, she was in Mech-X4 and she talked to Ryan and Mark about them being the pilots of Mech-X4. She rejected them and went to Seth in the monster.
    • When Grace tried to fight the monster in her brain, she was in the Med Bay sleeping. Leo was watching her so she doesn't see where she was.
    • After she woke up, she didn't remember having a monster inside her brain.

East Bay City High

  • In Versus The Outbreak, Grey tested the ooze Seth made that would turn East Bay City High to monsters. She mixed the ooze with the chocolate the dinner lady was making.
    • It doesn't work and they were just after the remaining students who weren't infected.
    • Its weakness was freezing cold. The Mech-X4 team used Mech-X4's Cold Cannon to blast the students with the freezing cold.



Kim Grey

Creating Monsters

Primorphous Gel is a source for creating monsters. There are different checkpoints where a pile of Primorphous Gel can be found. If a Primorphous Core ("monster heart" by the Mech-X4 team) is inserted into the gel, it takes a couple of time before a monster can grow. However, if the monster is defeated, the monster turns back to Primorphous Gel ("monster ooze" by the Mech-X4 team) and the Primorphous Core dries out.

If the gel is zapped by the X-Weapon, a human could turn into a monster once they fall into the ooze.