Sarah the Scarer

Yes, Sarah is technically in her forties, but the reason she retains her glow is because she was transformed at the peak of her youth. Legend says that when she was sucking the blood of a soon-to-be author (who thought she was having a dream), Sarah inspired one of the most famous lines of modern literature:
“How old are you?”
“Seventeen.”
“How long have you been seventeen?”
“...A while.”