Mordea

Mordea is the ruling Tempest of Pagan when the Avatar arrived in Ultima VIII. She is the daughter of Keldan and Celidia. But since she isn't the first-born, that is her half-brother Devon, she hasn't the full power of Tempestry. The feeling of being less powerful made her cruel and cold.

When the Avatar arrived in Ultima VIII, Mordea had already been Tempest for some time, and had erected a tyranny. The people of Tenebrae lived in constant fear of being executed, result of Mordea's paranoia. She also broke many traditions in her hunger for more power, especially disrupting the work of the Necromancers by taking away their Ritual Dagger. The city was paralyzed in fear, as everyone suspected of being against her rule was executed, as happened with Toran and Bentic during the game.

Her end came, when she tried to execute Devon, to become the only living Tempest. The Avatar discovered the truth of Devon's parentage, and revealed it to him, just before the execution. Devon, aware of his power, casted Mordea into the waters in battle, where she found her death at the teeth of the Lurker's minions.

Lore
''Ruler and Tempest of Tenebrae, our Lady Mordea governs with strict attention to detail. Her right of rule was inherited from her Tempest father, Keldan, and noble mother, Celidia - both royalty and real power support her claim to rulership. Our Lady is extremely aware of her position, accepting only the utmost in loyalty from her subjects.''

-from "Chronicle of Pagan", Ultima VIII

Trivia

 * Mordea can't be killed in combat and strikes down the Avatar with a lightning bolt.