Yep, Bellatrix.
"Yes, indeed, most admirable," said Snape in a bored voice. "Of course, you weren't a lot of use to him in prison, but the gesture was undoubtedly fine-"
"Gesture!" Bellatrix shrieked; in her fury, she looked slightly mad. "While I endured the dementors, you remained at Hogwarts, comfortably playing Dumbledore's pet!"
Ch. 2, HPB, Spinners End, Pg. 27, etc.