"Ulik, the Unstoppable Troll"; "Ulik, the Unconquerable Troll"
The general populace of Earth is unaware of Ulik's existence
Thor #137 (1968)
Ulik was also responsible for the release of Mangog, a monster that was said to possess the combined hatred of billions of beings killed by Odin and the Norse Gods. Mangog was nearly unstoppable and had aided various evil beings, most recently the mad Titan Thanos. Ulik may have appeared to be a mindless bruiser, but he was ambitious. Proclaiming that only Geirrodur could command him, Ulik had tried to wrest the throne from him more than once. He led several invasions of Earth through interdimensional portals, only to suffer defeat at the hands of Thor and Earth's other heroes. Once, after failing in an invasion attempt, Thor sealed the portal with molten rock. Geirrodur then banished Ulik to the furnaces of the Rock Troll Kingdom. After escaping, Ulik found another realm of trolls. By dispatching of their ruler, Ulik took control of this realm and continues his pursuit of revenge upon Thor and the other Asgardians.Perhaps his most embarrassing defeat occurred on Earth. After overpowering both Thor and Hercules, the son of Zeus, he was bested by a mortal police officer named Lt. Marcus Stone. Unloading all of his ammunition upon Ulik, Stone then arrested him like an average criminal.