At least two ships of the Hellenic Navy have borne the name Poseidon (Greek: Ποσειδών), after the ancient Greek god of the sea Poseidon:
- Greek submarine Poseidon (S-78) a Gato-class submarine launched as USS Lapon in 1942 she was renamed on transfer to Greece in 1957. She was stricken in 1976.
- Greek submarine Poseidon (S-116) a Type 209 submarine commissioned in 1979.
This article includes a list of ships with the same or similar names. If an internal link for a specific ship led you here, you may wish to change the link to point directly to the intended ship article, if one exists.