Sphacteria (Greek: Σφακτηρία - Sfaktiria, in 19th century context also Sphagia) is a small island at the entrance to the bay of Pylos in the Peloponnese, Greece. It was the site of three battles:
- the 425 BC Battle of Sphacteria in the Peloponnesian war.
- the 1825 AD Battle of Sphacteria in the Greek War of Independence from the Ottoman Empire
- the 1827 AD Battle of Navarino, also in the Greek War of Independence