Harry Potter and the Half-Blood Prince
"The Death Eaters can't all be pure-blood, there aren't enough pure-blood wizards left," said Hermione. "I expect most of them are half-bloods pretending to be pure. It's only Muggle-borns they hate, they'd be quite happy to let you and Ron join up." (21.147)
Death Eaters are a group of wizards and witches who work for Voldemort. They all wear the Dark Mark on their left arms. The Death Eaters hope to rid the Wizarding community of any non-purebloods. They also are hoping to take over the Ministry of Magic and to inspire fear across the land. Hermione rightly questions the supposed fact that every Death Eater is pureblooded. Purebloods are few and far between and growing fewer. So who exactly are these Death Eaters?