Charlus Potter's son

The son and only child of Charlus Potter and Dorea Black was a pure-blood wizard.

Nothing else is known about him, though it has been speculated that he is in fact James Potter I, Harry Potter's father. J.K. Rowling has commented that James’s parents were older when they had him; because of this, and because of his family’s wealth and lack of other children, he was quite spoiled. Dorea would have been forty years old in 1960, when James was born, which fits in with Rowling’s comments. However, she also said that James’s parents died of natural causes when they were elderly, but Dorea Potter née Black was only fifty-seven years old when she died. This could simply be a mathematical error, as Rowling has also admitted that math is not her strong suit and inconsistencies have been noted in the timeline. Also, many other members of the House of Black are shown to have died at relatively young ages for wizards, and James Potter's parents must have died between 1975 and 1981.

When he was going to Hogwarts School of Witchcraft and Wizardry for his first year, James Potter stated that his father was in Gryffindor but did not mention his mother, which would make sense if his mother was Dorea Black, who was in Slytherin house.

It is equally possible that Charlus, Dorea, and their son were simply relatives of James Potter and his father and mother.

Behind the scenes

 * If James Potter was indeed the son of Charlus and Dorea Potter, his son Harry would be related to many of those close to him. His godfather Sirius Black would be his second cousin, and his friend and wife Ron and Ginny Weasley, respectively, would be his third cousins. Also, Harry's godson Teddy Lupin would be his second cousin, twice removed. Harry would also be a cousin of Bellatrix Lestrange, Narcissa and Draco Malfoy, Andromeda and Nymphadora Tonks, and Regulus Black.