SIU
- Cristiano Ronaldo
- S.I.U. (film)
- SIU (Album)
- Scotland in Union
- Seafarers International Union of North America
- Shao
- Shinawatra University
- Siuna Airport
- Southern Illinois University
- Southern Illinois University Carbondale
- Special Investigating Unit
- Special Investigations Unit (disambiguation)
- Symbiosis International University
- Torres Strait Islanders
- Tower of God
- Xiao (surname)