The father of James Potter and the inventor of Sleekeazy’s hair potion (Pm).
Fleamont Potter inherited the Cloak of Invisibility from his father, a direct descendant of Ignotus Peverell (Pm). When he went to Hogwarts was sorted into Gryffindor house, like his son and grandson (DH33).
He created Sleekeazy's hair potion, the sale of which added to the family's already vast wealth. When he retired, he sold the company for an enormous profit (Pm).
He and his wife Euphemia had only one child, James Potter, who was born somewhat miraculously in their old age and whom they spoiled (Pm, JKR). When James's friend Sirius was disowned by his family, Fleamont and Euphemia took him in as a second son (OP6).
Fleamont and his wife lived long enough to see James marry Lily Evans, but neither got to meet their grandson, Harry Potter, before the died of Dragon pox in their old age (Pm).
Father: Henry "Harry" Potter, an outspoken member of the Wizengamot
Mother: A woman whose maiden name was Fleamont, after whom he was named.
Spouse: Euphemia Potter
Children: James Potter
Grandchildren: Harry Potter
Fleamont was a skilled potioneer, having invented Sleekeazy's hair potion.
He was also a strong duellist because he often got into fights with fellow students at Hogwarts who teased him about his name.