Vin is a character from the Mistborn trilogy, a half-skaa mistborn.
Spoilers for Mistborn.
Vin was born to a high Obligator and his skaa mistress, and got the powers of a mistborn from her father. Vin was at young age chosen by Preservation as the heir to his powers. She was discovered as a Mistborn by Kelsier, who trained her, and, after his death, she slew the Lord Ruler, after discovering his great secret.