Did anyone know Voldemort was a half-blood?

So the ones who did know knew not to mention it. The fact that death eaters like Avery and Lestrange knew his name does not conclude that they knew he was a half-blood. “I though you was that Muggle” whispered Morfin “You look mighty like that Muggle”.

Did any of the Death Eaters know Voldemort was half-blood?

Voldemort is a mixed blood wizard, also known as a half-blood. Most Death Eaters probably do not even know this little tidbit about Lord Voldemort, as Harry Potter only found out because Dumbledore told him, based on rigorous research that Voldemort had done.

Did Voldemort know about Snape’s biological history?

Voldemort was not of pure blood either. He most likely knew Snape’s biological history. Moreover, Voldemort could not judge a wizard of Snape’s potential based on a value system they both shared equally. The main problem Voldemort had was not so much with mixed blood wizards and witches but with pure blood muggles with magical abilities.

Did Dumbledore know that Snape was not a pure blood?

Yes he did know that Snape wasn’t a pure blood, but he still kept Snape around firstly because He thought Snape was acting as Voldemort’s spy in Hogwarts to keep an eye on Dumbledore.

Did Voldemort’s Death Eaters know that he was a Half-Blood?

Canon seems to conflict a bit on whether Voldemort’s Death Eaters knew that Voldemort was a half-blood. In Half-Blood Prince, Tom Riddle refers negatively to his parentage and it reads as if his fellow Slytherins found it amusing in a derisive way, even though Salazar Slytherin was the ancestor of Tom Riddle (HBP – chapter 23 – Horcruxes).

How did Voldemort feel about his parents?

So Voldemort resented his parentage and was jealous of the wizards and witches who hailed from pureblood families. He also was negatively influenced by living in a muggle orphanage, where Tom Riddle Jr was disliked by the other students.