Richard de Vernon seigneur de Redvers, 1st feudal baron of Plympton in Devon, was a Norman nobleman who may have been one of the companions of William the Conqueror during the Norman conquest of England from 1066. His origins are obscure, but after acting as one of the principal supporters of Henry I in his struggle against his brother Robert Curthose for control of the English throne, de Redvers was rewarded with estates that made him one of the richest magnates in the country. He was once thought to have been created the first Earl of Devon, but this theory is now discounted in favour of his son Baldwin.

The feudal barony of Plympton was a large feudal barony in the county of Devon, England, whose caput was Plympton Castle and manor, Plympton. It was one of eight feudal baronies in Devonshire which existed during the medieval era. It included the so-called Honour of Christchurch in Hampshire, which was not however technically a barony. The de Redvers family, first holders of the barony, were also Lords of the Isle of Wight, which lordship was not inherited by the Courtenays, as was the barony of Plympton, as it had been sold to the king by the last in the line Isabel de Redvers, 8th Countess of Devon (1237–1293).