|This article is about a/an monster in Power Rangers Lost Galaxy.|
Under the pretense of peace, Captain Mutiny offered to help the colonists, alluding to have a machine that would allow Terra Venture to escape The Lost Galaxy. Despite his reseverations, Commander Stanton agree to the help and sent Mike and several GSA soldiers to retrieve the device. On Mutiny's planet, the Swabbies loaded a giant crate wrapped in chains onto the Heliship, Mutiny handed Mike a small key, saying everything they needed was inside the crate. Unaware that Mike had been followed by the Galaxy Rangers, Mutiny unknowingly revealed that the contents inside the crate would enslave the colonists.
As Leo and the others prepared to depart, one of the slaves noticed them on the hill above and begged for help, giving their position away to Mutiny and Barbarax. Mutiny ordered Barbarax to send Rocketron after them in order to keep their plans from being revealed to the colonists. While the Rangers defeated Rocketron, they arrived too late to stop Stanton from opening the crate and releasing Grunchor, who attacked the moment it was released from imprisonment and burrowed under their streets.
Barbarax was confident that Grunchor would not be defeated by the Rangers, citing that it was "too big to beat", despite Mutiny's concerns. The monster continued to burrow underneath the streets of the colony and terrorized its citizenry until it was summoned from underground by Barbarax. The Ranger's first assault on the monster proved fruitless, their combined powers causing it mutate and grow into a stronger being. Calling on the Megazords, the Rangers and the Magna Defender continued the battle from there.
As Torozord restrained Grunchor, the Galaxy Megazord slashed with its saber, but the blow was useless against Grunchor. Mutiny's Castle docked on Grunchor's head and the Rangers continued to be overwhelmed by the monster's strength, Torozord was defeated in one blow, while the Stratoforce and Centaurus were damaged protecting the Galaxy Megazord from an energy blast, despite the use of Leo's fire abilities. Finally, the Rangers decided to pool their strength into Leo's fire ability since Deviot had told them that Grunchor's only weakness was fire. With the power of the other Rangers and the Centaurus and Stratoforce Megazords strengthening him, Leo unleashed his Galaxy Fire Power upon Grunchor, ultimately disintegrating him.
- When Grunchor moves about under the streets, it similar to the Graboids from the Tremors franchise.