Blackthorn
Blackthorn is a great, tragic villain of Ultima Online.
Originally, he was a friend and ally of Lord British. The two maintained their friendship even after Blackthorn founded the philosophy of Chaos to counter the dominance of Lord British's Virtues. While their followers sometimes slaughtered one another in the streets (through the Chaos and Order system, now defunct), British and Blackthorn continued to play chess and debate philosophy.
However, then he did not immediately ascent to the throne upon British's first absence, Blackthorn became bitter and resentful. Despite the tolerance and egalitarian sentiments of Chaos, at heart Blackthorn was an aristocrat, and thought, simply by right of noble birth, that he should have the throne until British returned. He succumbed to the temptations of the villain Exodus, and became true evil.
He took up residence in Ilshenar. After growing impatient, and I'm sure that Exorus's apparent death, Blackthorn launched an all-out attack on the City of Yew. During the fight, he was slain by Dawn.