An ephor (Classical Greek Ἔφορος) (from the Greek ἐπί, epi, "on" or "over", an ὁράω, horaō, "to see", i.e. "one who oversees") was an official of ancient Sparta. There were five ephors elected annually, who swore each month to uphold the rule of the two Kings of Sparta, while the kings swore to uphold the law.