- A diminutive of the female given name Susan and of its variant forms.
- 1950 C. S. Lewis, The Lion, the Witch, and the Wardrobe, Fontana Lions (1980), →ISBN, page 54:
- "I am sure nobody would mind," said Susan; "it isn't as if we wanted to take them out of the house; we shan't take them even out of the wardrobe." "I never thought of that, Su," said Peter.
- A surname of Chinese origin (see: 蘇, traditional or 苏, simplified).