Siwa may refer to:
- 140 Siwa, an asteroid
- Siwa, Indonesian pronunciation of the Hindu god Shiva
- Siwa (genus), spider genus in the Araneidae family
- Siwa Oasis, an oasis in Egypt
- Siwa, Panchthar, a Village Development Committee in Nepal
- Šiva, Slavic goddess of fertility
- Siwa, a Finnish retail chain of convenience stores, partly owned by Tradeka and Elanto.
- Siwa culture, a Bronze Age nomadic culture in the Gansu Province, China