South Petherwin (Cornish: Paderwynn Dheghow) is a village and civil parish in east Cornwall, England, United Kingdom.

The district falls in the Altarnun electoral ward but the population of the civil parish at the 2011 Census was almost unchanged at 931.

The parish church, dedicated to St Paternus, stands in the village at grid reference SX 309 819.

It is with the Saxons that both Petherwins began to dominate the region, with the River Kensey being the natural divide.

The tower has three stages, and is buttressed on the square; it is wholly built of local stone apart from the battlements and pinnacles which are of granite.

There was a holy well in a field at Oldwit Farm, where water was collected and brought to the church each time a baptism took place.

[5] Stanley Simmonds was an English painter and art teacher who retired from teaching in 1983 and he and his wife moved to South Petherwin (near Launcestion where his friend Charles Causley lived).

[6][8] Retrospective exhibitions of his work were held in Launceston in 2012, organised by the Charles Causley Society,[9] Lewes in 2014[10] and Egdean, Sussex, in 2015.