- Weight: 100,000 tons (estimated)
- Regular Abilities: Growth from biological toxins and radiation
- Special Abilities: Burrowing, could emit fire or toxin blasts from his mouth and also create large shockwaves by slamming his head into the ground in the Game Boy Color adaption of Monster Wars
El Gusano Gigante is an hitherto unknown species of worm that first appeared in episode 4. It fed off a rare poisonous plant which enabled it to grow to incomprehensible worm proportions. When the local government attacked with a bio-weapon filled with toxins from it's food source it grew bigger and stronger.
Mutations after bio-weapon exposure:
- Claws on it's arms
- Paler skin
- Plumper muscles
- Enlarged and wrinkled horns and spikes
However, despite El Gusano Gigante's power boost, the annelid monstrosity was soon defeated by Zilla with a blast of his atomic ray, after which it shrunk to the size of a normal worm, and disappeared. It later appeared during the Tachyon alien invasion, in the Monster Wars story arc. The gigantic worm was unleashed by the aliens to attack the city of Moscow during the battle, where the monster used its burrowing abilities to harass the Russian armed forces. When the aliens lost control of the beasts, it was killed by their capital ships in order to regain control.