Omer, in the Book of Mormon, was a Jaredite king whose reign was troubled by rebellion and secret combinations. The story of Omer's reign, overthrow, regaining the throne, overthrow, and eventual return to the throne is told in the Book of Ether, chapters 8-9.
Reign and intrigue
In chapters 8 - 9 of the Book of Ether (part of the Book of Mormon), the following is related of the life of Omer:
Omer was the son of Shule who was king of the people of Jared. Omer had a son whom he named Jared. Jared moved to a land called Heth. After some time, he was able to convince half of the people of the kingdom to support him and he overthrew his father, Omer.
Omer was kept captive, during which time "he begat sons and daughters, among whom were Esrom and Coriantumr". Esrom and Coriantumr raised an army with which they defeated Jared's army. They were about to slay Jared when he convinced them to spare his life.
However, Jared still desired to be king, so his daughter devised a plan to regain the throne which they carried out. Jared's daughter danced for a man called Akish who then desired to marry her. Jared agreed, on the condition that Akish "will bring unto me the head of my father, the king." Akish gathered Jared's kinsmen, had them swear an oath to follow him and agree that anyone revealing the plan would be killed.
Akish and those loyal to him took the kingdom from Omer. However, Omer and his children (who hadn't plotted against him) fled past the hill Shem to a place called Ablom along the seashore. Jared became the king, but Akish plotted against him too and had Jared killed. After assuming the throne, Akish had one of his sons shut up in prison without food until he died.
Nimrah, brother of the man starved to death, was angry at his father because of this. Nimrah gathered together some others, left the kingdom and moved to where Omer was living.
Akish's sons desired power, so they paid most of the people to join their faction. This faction and those loyal to Akish fought "for many years" until there were only thirty people left. Omer was then restored to the throne (again), he anointed his son Emer to be the king, and lived two more years.