The feudal barony of Plympton (or Honour 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 (now in Dorset), 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).
Many of the lands which later formed the feudal barony of Plympton were formerly held by two Devon Domesday Book tenants-in-chief of King William the Conqueror (1066–1087):
The descent of the feudal barony of Plympton was as follows:
The barony comprised originally the following manors held in-chief per baroniam: