Paladin Jonathan

Jonathan Maxson is the father of Arthur Maxson and husband of Jessica Maxson. He and his wife died when their son was still very young, making Arthur the last of the Maxson Dynasty at the time of Fallout 3. The cause of his death is not specified.

Background
Jonathan is not only a descendant of Roger Maxson, the founder of the Brotherhood of Steel, but he was also a high-ranking Paladin just outside New California Republic. He was, however, killed in battle. It is possible that, being the father of Arthur Maxson, who was born in 2267, John Maxson, who was born in 2097 and at the age of 65 in 2162, could very well be his father. However, if not, there's a pretty small gap of time in between the existence of John Maxson and the time Arthur was born, and little time for there to be a different grandfather, as one isn't mentioned in any of the games. It is also possible that Jeremy Maxson could be his father.

Appearances
Jonathan Maxson is mentioned in a terminal at the Citadel's library in Fallout 3. He does not actually appear in the game.