"Lord British was a player character created by Richard Garriott, the producer of Ultima Online. Using this character, Richard acted as Ultima’s King and would sometimes interact with other players. Lord British had considerable protection from an entourage of bodyguards and was even explicitly coded to be invulnerable to virtually any attack. During the game’s online beta test, Lord British gave an address to fellow players at his Castle Britannia. But while British was giving his address, a player character known as Rainz cast a spell scroll that set the Lord on fire, killing him instantly.
"It turns out that shortly before this event, the server had crashed and needed to be restarted. Garriott forgot to reimplement his invulnerability flag, leaving him open to being killed. If that wasn’t shocking enough for the attendees, a fellow developer of the game known as Starr Long, with his in-game character Lord Blackthorn, summoned a horde of demons to kill the assassin. Not only did the assassin manage to escape, but the demons had killed nearly every player attending the address..."
[1] - https://www.cbr.com/ultima-online-lord-british-assassination...