San Román de Sau (in Catalan: Sant Romà de Sau), is a town in the municipality of Vilanova de Sau in the region of Osona.
Its origins place the town of Sau in 917. The parish church was built in the 11th century. The present town was formed when the Sau reservoir was built in 1963 to cover the old town. Despite being practically abandoned since 1860, where it was reported that the parish was uninhabited. It had a few farmhouses, a Romanesque bridge and a parish church (now partially demolished) which reappears in times of drought.