Valentano is a town and comune of the province of Viterbo, in the Lazio region of central Italy. It is 33 kilometres (21 mi) from the provincial capital, Viterbo.

The placename is of uncertain origin. Some identify the town with an Etruscan Verentum, others trace the name to ontano, Italian for alder, since alders cover the slopes of a nearby valley: Valle Ontano becoming Valentano.