Grundor the Greater was the king of the Rock Trolls that would come into conflict with Thor when the trolls raided the countryside of Asgard. Thor was captured but he managed to escape and fight back against Grundor and his forces. Grundor reveals to Thor that a demon from the lower caverns called Uroc forced the trolls to head to the surface world to attain food. Uroc the Uru Monster reveals himself to Thor and Grundor when they enter his domain. Uroc's entire body is composed of indestructible uru metal and is able to withstands Thor's attack. Grundor tells Thor that Uroc was a weaponsmith and forced him to create a powerful weapon for his leader or suffer dire consequences. Uroc found a vast amount of uru metal and constructed this monstrous form where he would transfer his consciousness into it through sorcery. Uroc would force the trolls from the caverns below towards the surface world where they initially came into conflict with Thor. Thor was able to defeat Uroc when the monster smashed a stone bridge over the Chasm of Eternal Sorrow and he fell towards a bottomless chasm. Grundor is thankful to Thor for saving his life and offers his friendship to the thunder god.
Grundor was created by Tom DeFalco
and Mike Mignola
in 1989 and first appeared in Thor