Grymmdjarr was the first lord of Ard Skellig and founder of Clan an Craite. He was famed for his incredible strength. When he traversed the isle for the first time and found no place worthy of making his seat, he asked Hemdall to give him the thickest chain he could forge.
Once he received the chain, Grymmdjarr dove into the depths of the sea and used it to drag an enormous rock to the surface, placing it on Ard Skellig's north-eastern shore. Then he carved Kaer Trolde out of this rock with his bare hands, and there it stands to this day, the pride and glory of his clan.