Harry and Draco are related very distantly and only speculatively. It is possible that Harry and Draco share great-grandparents, this would make them distant cousins. However, this evidence is conjectural and taken from one name on the Black family tree; Charles Potter who married Dorea Black, Draco's great-great-aunt and possible grandmother to Harry. read more
Screenshot Cedrella Black married Septimus Weasley and had 3 children with him, presumably (and a lot of facts point toward this) one of them being Arthur Weasley. read more
Draco is related to Sirius through Bellatrix Lestrange as she is Sirius’s cousin. Since Sirius is Harry’s godfather, they are related that way, but not by blood. Also, being Teddy Lupin’s godfather, Harry is related to the Malfoys, as Narcissa and Andromeda (Nymphadora’s mom) were sisters. read more