harry potter - Do vampires exist in the Potterverse?

Do vampires exist in the Harry Potter universe? Characters mention them at a few places, but we never meet an actual vampire, and I'm starting to think they are only a legend even in that universe.

We've had lots of opportunities for vampires to turn up, even for just an insignificant role, during the series, but it never happened. The students never seem to learn about vampires during their classes. Dumbledore has allowed a werewolf to study at Hogwarts safely, and sent Hagrid to contact the giants. Hagrid has supposedly grown werewolf cubs under his bed. The statue in the ministry shows a goblin but no vampire. We meet people with strange magical illnesses, including a werewolf bite, in St Mungo's hospital. Centaurs and merfolk turn up to pay respect on Professor Dumbledore's funeral – wouldn't an army of vampires circling over his grave have been a great sight? The Dark Lord has tried to get various strange creatures as allies, such as giants, Dementors and a werewolf. Some of these fight at the battle of Hogwarts. Some fans have suggested that Professor Snape could be a vampire, but that was before Hallows was published, and Hallows disproves the theory. If vampires never appear during all this, I think that's because they simply don't exist.

Let me collect some places where vampires are mentioned.

• In Stone chapter 5, Hagrid mentions Professor Quirrell met vampires in the Black Forest. Stone chapter 8 mentions again that everyone says Quirrell's classroom smells of garlic to ward off a vampire he'd met in Romania. We, however, know that the Professor was lying about at least some of the details about his travels.


• In Chamber chapter 4, we learn that one of Lockhart's books is titled Voyages with Vampires. His books don't always tell the truth though.


• In Prisoner chapter 22, Dean Thomas hopes they'd get a vampire as the new Defense Against the Dark Arts teacher next year.

See the related question What is a hag in Harry Potter? .

Answer

In Half-Blood Prince at Slughorn's holiday party, Sanguini the vampire is a guest in attendance.

‘Harry, I’d like you to meet Eldred Worple, an old student of mine, author of Blood Brothers: My Life Amongst the Vampires – and, of course, his friend Sanguini.’

Worple, who was a small, bespectacled man, grabbed Harry’s hand and shook it enthusiastically; the vampire Sanguini, who was tall and emaciated with dark shadows under his eyes, merely nodded.

_{Half-Blood Prince - page 295 - Bloomsbury - chapter 15, The Unbreakable Vow}

I particularly like this bit:

'Sanguini, stay here!’ added Worple, suddenly stern, for the vampire had been edging towards the nearby group of girls, a rather hungry look in his eye. ‘Here, have a pasty,’ said Worple, seizing one from a passing elf and stuffing it into Sanguini’s hand before turning his attention back to Harry.

_{Half-Blood Prince - page 296 - Bloomsbury - chapter 15, The Unbreakable Vow}