Septimus Weasley

Septimus Weasley was a pure-blood wizard who married Cedrella Black. Because he was considered to be a blood traitor by the Black family, the marriage caused Cedrella's removal from the Black Family tree. The couple had three sons, including Arthur Weasley. He was the father-in-law of Molly Weasley, paternal grandfather of Bill, Charlie, Percy, Fred, George, Ron and Ginny Weasley, great-grandfather to James, Albus and Lily Potter, Victoire, Dominique, Louis, Molly II, Lucy, Fred and Roxanne Weasley and Rose and Hugo Granger-Weasley.

Etymology
Septimus is a name of Latin origin. It means seventh.