A Shadow Siren from Paper Mario: The Thousand-year Door. First confirmed transgender character in the Mario series - the English localization of the original game changed this, but it was restored in the remake.
Vivian is very shy and self-conscious. Her sisters, particularly Beldam, constantly belittle her by calling her male terms despite her protests, though she is too shy to stand up for herself. She defects from her sisters to join Mario's party and ultimately help him defeat her supposed master, the Shadow Queen, learning to respect herself more along the way.
