Mighty Gross (マイティグロース Maiti Gurōsu) is a monster creation of Mad Go-Ne that appeared in the series Jumborg Ace.
Subtitle: Cyborg Dinosaur (サイボーグ恐竜 Saibōgu Kyōryū)
Mighty Gross was sent by Mad Go-Ne on a mission sent to destroy the PAT base. PAT quickly discovered this, intercepted Mighty Gross and fired missiles at him as he strolled through a small canyon. Mighty Gross pressed on, soon destroying a bridge with his head as the assault continued followed by his missile cannons shooting a PAT jet down. Mad Go-Ne ordered Mighty Gross to go underground while still moving toward the base. The beast soon emerged and fired his missile cannons to cause a rock slide as PAT was unable to even distract him. He almost succeeded until Jumborg Ace appeared, flying at the long necked monster. Mighty Gross fired his missile cannons, but Jumborg Ace out maneuvered him with ease followed by using the Emerald Blast on the back of the head. The robot hero wrestled with Mighty Gross when his left fist got stuck in a back suction cup. Once he freed himself, Jumborg Ace grabbed the beast by the tail and threw him. After some kicks and another throw were done, Might Gross was decapitated by the Heading Killer and exploded.
- His roar is a modified Red King roar.
- Design: Yoshiaki Yoneya
- Design motifs are Apatosaurus (its shape) and barnacles (its back).
- Mighty Gross' ghost would appear in the monster graveyard fighting Jumborg Ace while Wutan attacks Earth.
- Length: 90 m
- Weight: 39,000 t
- Origin: The Foot of Mt. Chichibu
- Powers and Weapons
- Missile Cannons: Mighty Gross has a missile cannon on his face.
- Burrowing: Mighty Gross can burrow at low speeds.
- Suction: He can suck objects like his enemies' arms into barnacle-like holes on his body.