It is perhaps interesting that Voldemort himself is not a pureblood; while his mother, Merope Gaunt, was a member of one of the oldest Wizarding familes in existence, his hated father was a “Mudblood”. In spite of this, he is still considered the heir of Salazar Slytherin.
Voldemort's obsession with blood purity signifies his aim to rid the wizarding world of Muggle (non-magical) heritage and to conquer both worlds, Muggle and wizarding, to achieve pure-blood dominance.
Yes, they did. The Riddle surname is not a Pureblood name, and it's a name that Tom had at school. Ergo, the other Purebloods knew that Riddle was not a Pureblood. The Pure-Blood Directory also came out in the 1930's, and 'Riddle' was not one of the names listed on there.
Harry James Potter holds half-blood status in Rowling's imagined wizarding world because his mother is Muggle-born and his father is pure-blood. There are three main blood statuses; pure-blood, half-blood, and Muggle-born, which are all methods of determining a witch or wizard's magical lineage.
(sorc.), S. of Mag.Q. (August 1881 – 30 June 1997) was an English half-blood wizard. He was the Defence Against the Dark Arts Professor, later the Transfiguration Professor, and later the Headmaster of Hogwarts School of Witchcraft and Wizardry.
The Longbottoms
Neville comes from a long-line of pure-blood wizards, although we don't know as much about the individuals as we do with some other wizarding families. What we do know is that both of Neville's parents were pure-blood, as was his gran, Augusta.
Luna Lovegood is a Pureblood witch, who was sorted into Gryffindor House during Harry Potter's second year at Hogwarts School of Witchcraft & Wizardry.
The Weasleys are poor because of having 7 children. Until Bill and Charlie started working, the Weasley family had one earning member to take care of the household expenses, education and upbringing of 9 family members.
The pure-blood wizards and witches featured in the Harry Potter books are almost all supremacists, while there are some of them who do not advocate ancestral superiority; the Potters, Weasleys, and Longbottoms are old pure-blood families, but no known members of these families are sympathetic to supremacist aims.
Lord Draco Lucius Malfoy (born 5 June 1980) is a pure-blood wizard; the second son and third child overall of Lucius Malfoy II and Narcissa Malfoy (née Black).
His viciousness to Muggle-borns is connected: Riddle may be half-blood, but Muggle-borns can claim no wizarding heritage, therefore to him they are as low as Muggles themselves. Riddle also hates Muggles because they remind him of his childhood and the Muggle father who deserted him.
Bellatrix Lestrange (née Black) is the first female Death Eater introduced in the books. Aunt of Draco Malfoy and Nymphadora Tonks. She was introduced in Harry Potter and the Order of the Phoenix. She is the most faithful member of Voldemort's inner circle.
Snape was born to Eileen Prince, a witch, and Tobias Snape, a Muggle, making him a half-blood (hence the name, "Half-Blood Prince"). This is rare for a Death Eater, as remarked in the last book, though Voldemort himself also had a Muggle father.
“Until the imposition of the Statute of Secrecy in 1692, the Malfoy family was active within high-born Muggle circles, and it is said that their fervent opposition to the imposition of the Statute was due, in part, to the fact that they would have to withdraw from this enjoyable sphere of social life.”
Voldemort was Salazar's heir, and as far as it is explained, he is taking up the mission in the way he believes Salazar had intended, with the Chamber and the Basilisk.
One of the wealthiest Wizarding families in Britain, the Malfoys were known for their connections to other pureblood families and their covert influence over the magical government. In contrast to the Weasleys, the Malfoys were traditionally sorted into Slytherin and supported pureblood supremacy.
He's a pure-blood wizard, proud Slytherin and Harry Potter's arch rival at Hogwarts. Happy birthday, Draco Malfoy!
The story of Chamber of Secrets, as you know, is that the Heir of Slytherin has returned and he's out for Mudbloods. The Heir of Slytherin turns out to be Ginny Weasley, who is being controlled via a magical diary that once belonged to Tom Riddle, AKA Voldemort.
In some cases (the Malfoy family) blood traitors are a bad as Mudbloods. As other people said, it is also due to the Malfoys' arrogance, the feeling of self-importance and wealth. The Weasly family is also very poor, which may also lead to a dislike with the rich, pureblood families.
This idea was incredibly embarrassing to him since Ron vehemently did not want to be cared for by his rich and famous best friend. This is precisely why Harry never tried to give the Weasleys money or give Ron lavish gifts - they didn't want pity.
Luna was continually teased at Hogwarts for being eccentric, for being a bit of a free agent and for following the beat of her own drum, so much so that she was perceived as being not all there. Other students nicknamed her 'Loony' and we would wager that this connection isn't a coincidence.
Astoria Malfoy (née Greengrass) (c. 1982 - 2019) was a pureblood witch.