Selwyn family

Selwyn is the surname of a wizarding family that is most likely pure-blood.

Dolores Umbridge claimed to be related to the Selwyns in 1998, lying about how she obtained an ornate locket. Umbridge took it as a bribe from Mundungus Fletcher, but told Hermione Granger, who was disguised as Mafalda Hopkirk through use of Polyjuice Potion, that it was an old family heirloom. She was likely lying to "bolster her own pure-blood credentials"; however, it is unclear whether Umbridge was lying about the blood status of the family, or merely her own relation to them.

There is a Death Eater who has the surname Selwyn, which may further suggest that the Selwyns are a pure-blood family.