Bellatrix Lestrange

“Someone's dead," said Malfoy, and his voice seemed to go up an octave as he said it. "One of your people...I don't know who, it was dark...I stepped over the body...I was supposed to be waiting up here when you got back, only your Phoenix lot got in the way.”
― J.K. Rowling, Harry Potter and the Half-Blood Prince

“Enemies of the Heir, beware! You'll be next, Mudbloods!”
― J.K. Rowling, Harry Potter and the Chamber of Secrets

“You - will - never - touch - our - children - again!' screamed Mrs. Weasley.
Bellatrix laughed, the same exhilarated laugh her cousin Sirius had given as he toppled backwards through the veil, and suddenly Harry knew what was going to happen before it did.
Molly's curse soared beneath Bellatrix's outstretched arm and hit her squarely in the chest, directly over her heart.
Bellatrix's gloating smile froze, her eyes seemed to bulge: for the tiniest space of time she knew what had happened, and then she toppled, and the watching crowd roared, and Voldemort screamed.”
― J.K. Rowling, Harry Potter and the Deathly Hallows

“Oh, he knows how to play, little bitty baby Potter.”
― J.K. Rowling, Harry Potter and the Order of the Phoenix