The Eubulides Paradox

According to Wikipedia Eubulides (Greek: Εὑβουλίδης; fl. 4th century BCE) of Miletus was a philosopher of the Megarian school, and a pupil of Euclid of Megara. He is famous for his paradoxes

His most famous paradox is The Liar (pseudomenos) paradox, which is similar to the famous paradox of Epimenides the Cretan. A man says: "What I am saying now is a lie." If the statement is true, then he is lying, even though the statement is true. If the statement is a lie, then he is not actually lying, even though the statement is a lie. Thus, if the speaker is lying, he tells the truth, and vice versa.

http://mathworld.wolfram.com/EubulidesParadox.html