A terrible giant slain by Gawaine. He inhabited a desert island and had the strength to move mountains.
Assiles and his foster son, Galaas, plagued King Flois of Effin, who enlisted Gawaine’s services as champion. Gawaine’s victory against the monster saved the castle of Eigrun.
Source
Diu Crône | Heinrich von dem Türlin, c. 1230