Joel Thomson is the son of Thomas and Suzannah Thomson. At her husband's urgings Suzannah tried to bring herself and her children to the distant land of Kalimdor in order to escape the undead scourge. However complications prevented them from leaving. Thomas, the future Headless Horseman, would come to the conclusion that a storm destroyed the last ship fleeing to Kalimdor.
In time the Thomson's hiding spot from the undead would come under attack by the paranoid and zealous humans of the Scarlet Crusade. Ironically enough the one to kill Joel, his mother and his sister would be his own father, who wouldn't recognize them until it was too late.