Nikolaos Emmanuel Mavromatos (Νικόλαος Εμμανουήλ Μαυρομάτος; born 15 November 1961 in Athens) is a Greek theoretical physicist, specialising in string theory, particle physics, and cosmology. He has an international reputation for his research on quantum spacetimes, uncertainty relations in string theory, and ideas for tests of possible violations of Lorentz invariance and CPT invariance.