Leoric was King of Evermore during the time of the Interregnum. Before the foundation of the Daggerfall Covenant, he had been a well-renowned ruler and military leader for the Empire. He had manned the Bangkorai Pass with many expertly trained soldiers to protect High Rock from invading forces in Hammerfell, as well as Orcs and Goblins attempting to steal territory. While acclaimed for these feats, his fame eventually came crashing down around him.
His son fell ill and died, and in his mourning, he began to change. He doubted the efforts and skills of his healers and began conducting intense and rigid inspections of the practices of the healers in his city. One by one, they were expelled from the city for failing to measure up to his standards. His standards, however, were not realistic, and when people continued to not measure up, he took greater efforts to inspire harder work. Soon, healers were being executed. Doubt began to rise in his leadership and he would be questioned in council meetings. All this did, however, was inspire in Leoric a sense of paranoia. He was sure, now, his people were betraying him. Soon, more executions began, not just of medical personnel, but also of government officials and his own soldiers.
He and his wicked-looking mace became a vision of terror throughout his land. With this taking up his time, he could not devote his attention to actually governing, or taking care of an even more important scenario, an invasion from the north, of the Reachfolk people. The invasion smashed into Bangkorai and eventually laid siege to the city of Evermoor itself. He died in the siege, but not at the blade of a Reachfolk, but at the blade of one of his own military captains.
After his death, the people surrendered and the Reachfolk took control of Evermore, but that would not be the end of his story. In the days after his death, through some means, he returned to life, seemingly. He walked among the living again, exacting even more severe acts of abuse and torture. For a time, the people of the kingdom banded together with the Reachfolk to fight against him, but they soon found themselves fighting the risen dead, former loved ones on both the Reachfolk's side and the people of Evermoor. It took several years for the people of High Rock to band together in order to take him out. Of course, with High King Emeric of Wayrest leading the charge, they also drove out the Reachfolk, but in the end, Leoric's terror was stopped.