1990 (aged 16)
Olwin Davies (1974-1990) was a Halfblood Witch. She attended Hogwarts School of Witchcraft and Wizardry from 1985-1990 and was sorted into Slytherin. She was diagnosed with Mooney Madness when she was seven, and was killed by it when she was sixteen.
Olwin is a variant of the Welsh name Olwen, which means "white footprint" from Welsh ol "footprint, track" and gwen "white, fair, blessed". In Welsh legend Olwen was a beautiful maiden, the lover of Culhwch and the daughter of the giant Yspaddaden. Her father insisted that Culhwch complete several seemingly impossible tasks before he would allow them to marry, and Culhwch was successful with all of them.