|First appearance:||Jumborg Ace Episode 15: "Storm Mad For MadGorne"|
Subtitle: Cyborg Dinosaur (サイボーグ恐竜 Saibōgu kyōryū?)
- Length: 90 m
- Weight: 39,000 t
- Origin: The Foot of Mt. Chichibu
Mighty Gross was sent by Mad Go-Ne on a mission to destroy PAT's base. He almost succeeded until Jumborg Ace appeared. Fighting Jumborg Ace, he was eventually decapitated by the Heading Killer.
Powers and Abilities
- Missiles: Mighty Gross can launch missiles from his face.
- Suction ability: He can suck objects like his enemies' arms into barnacle-like holes on his body.
- His roar is a modified Red King roar.
- Design: Yoshiaki Yoneya
- Design motifs are Apatosaurus (its shape) and barnacles (its back).