Nonius can refer to:
People Romans belonging to the Nonia gens Nonius Marcellus, a Roman grammarian of the 4th or 5th century AD Pedro Nunes (Latin: Petrus Nonius) (1502–1578), Portuguese astronomer and mathematician
Other Nonius (horse), a breed of horse Nonius (device), a precursor to the Vernier scale Nonius (crater), a lunar crater
See also Nonus Nonnus