Lord British
Lord British was once the King of Britannia. Initally, he was played by Richard Garriott, who is the creator of Ultima Online.
In the past, the NPCs of UO consistently, and with apparent sincerity, discussed their love of and respect for their King, which added to the fiction that the realm was well-governed and that Lord British was a benevolent ruler.
The fiction was that Lord British was somehow from the real world, as was the Avatar.
He originated the Virtues. His friend and political rival, Lord Blackthorn, invented a competing belief system called Chaos. Blackthorn eventually became corrupted and evil. The fanatical followers of each man fought in the streets as part of the Chaos/Order PvP system, while the two men played chess amicably and discussed philosophy.
Lord British had been unseen for some time prior to the announcement, which was made on March 30, 2000, that Richard Garriott had left OSI. After his initial departure, Blackthorn, furious with his not being appointed to the throne in Lord British's stead, struck an alliance with Exodus and turned "true evil".
Lord British returned again during the Age of Shadows expansion for a plotline involving Minax. However, it was not Richard Garriott that played Lord British in this instance. Garriott allowed UO to use his character on a temporary basis so as to develop an explanation for Lord British's long absence and permanent departure. Accordingly, Lord British left to take an undefined, yet powerful, artifact into the Ethereal Void, which would secure it beyond permanently Minax's grap.
In his stead, the realm is now ruled by the Britannian Council, which is loosely parliamentary, and/or by the role-played High Councils that exist on various, but not all, shards.
Trivia
During a speech on August 8, 1997, Lord British was killed. It was during UO's beta version when Lord British was killed by players who were using a combination of flame-based spells. The killing blow was a Flamestrike.
Accounts differ if the players used an Exploit, or if Garriott forgot to turn on his "invulnerable" flag. Either way, the killing player was banned, for this and for other naughty things done during the beta test. Richard Garriott also challenged his killer to a rematch in his more recent game project, "Tabula Rasa." So far as anyone knows, the challenged has not responded.
This event was used in the fiction for the Royal Leggings of Embers artifact.