There’s a list “The Sacred Twenty-Eight”, which supposedly lists all the pure-blood families in the land. We know this list isn’t complete (for example, the Potters are omitted), but it gives us somewhere to start.
Surviving to Harry’s year
On this list, we can identify several pure-blood families with children in Harry’s year (surviving families):
- Hannah Abbott
- Millicent Bulstrode
- Astoria and Daphne Greengrass
- Neville Longbottom
- Ernie Macmillan
- Draco Malfoy
- Marcus Flint
- Theodore Nott
- Pansy Parkinson
- Harry Potter
- More Weasleys than I care to list
These families may no longer be strictly pure-blood – for example, Harry is half-blood by Lily. However, the family names all survive.
All of these people are believed to have survived the Battle of Hogwarts, and so the family name continues. Several of the names are known to survive to the next generation (Potter, Malfoy and Weasley). We don’t know much about the extended families, so it’s possible that the families with no male heirs are soon to disappear.
Surviving beyond Harry’s year
Several family names survive, but only one is sure to be pure-blood:
- Harry and Ginny’s children continue the Potter name, but Harry’s half-blood status mean this is no longer a pure-blood family.
- Draco and Astoria’s son Scorpius continues the Malfoy line. They are both on the sacred twenty-eight, and the families have strong blood supremacist tendencies – Scorpius is pure-blood (perhaps one of the last truly pure-blood wizards)
- There are multiple children with the Weasley name, but I don’t think there are any spouses that we know are pure-blood. (The surnames we know don’t appear on the sacred twenty-eight, but that isn’t a guarantee.) Thus the name survives, perhaps not the blood purity.
Extinct or endangered
These are the families which have recently or will soon disappear:
- The Blacks – at the end of Order of the Phoenix, the last surviving member of this family is killed.
- The Crouches – the two remaining members of this family die in the course of Goblet of Fire.
- The Gaunts – the name died out sometime before Half-Blood Prince, and the last descendent was Tom Riddle. That family is well and truly squashed.
- Molly Weasley was the last person to have the name Prewett; the family survives although the name does not.
There are some families with no known children in Harry’s generation, and which are liable to disappear in the near future:
- A selection of Death Eater families: Avery, Burke, Carrow, Fawley, Lestrange, Rosier, Rowle, Traver, Yaxley
- Others: Ollivander, Selwyn, Shacklebolt, Slughorn