Grotogauros (グロデガウロス?) is a GurodegaurosuTerror-Beast kaiju created by Toho that first appeared in the 26th and final episode of Zone Fighter. Grotogauros is the final opponent to face Zone Fighter due to the cancellation of the series because of a lack of oil to use in pyrotechnics.
Grotogauros emerged once Hikaru had successfully defeated the entire Cobalt Garoga squadron, with the defeated aliens combining to form the monster. The battle from this point onwards was incredibly difficult - Zone Fighter was repeatedly beaten down by Grotogauros, and the monster's ability to use illusions only made the battle harder. Eventually, Zone Fighter managed to force his way past the illusions and defeated Grotogauros.
- Grotogauros is one of the most powerful Terror-Beasts, as a result of being a fusion of five elite Garoga X Agents.
- Grotogauros is very strong, and can throw around opponents with ease.
- Grotogauros can breathe a white mist from both his mouth and both nostrils.
- Grotogauros can self-destruct in a last-ditch attempt to take an opponent down with them.
Grotogauros reuses Jirass roars.