Sebastia (also Sebastea, Sebasteia; Greek Σεβαστεία) may refer to:
- Sebastia, Nablus, a Palestinian village in the West Bank
- Sivas (Latin: Sebasteia), an Ancient Roman city, now Sivas in Turkey
- Sebasteia (theme), a Byzantine province named after the city
- Malatia-Sebastia District, in Yerevan, Armenia
- Sebastia (moth), a moth genus