John de Cobham, 3rd Baron Cobham (died 10 January 1408) was the son of John de Cobham, 2nd Baron Cobham and Joan de Beauchamp. He was given a licence to crenellate by Richard II in 1381 and built Cooling Castle at the family seat in Cowling or Cooling, Kent.Around 1332, Sir John married Margaret Courtenay, daughter of Hugh Courtenay, 10th Earl of Devon. She died on 2 August 1385 or 95. In 1398 Sir John was exiled to Guernsey. Henry IV restored the estate and Sir John died in Cooling, 1408. He was buried at Grey Friars, London, though his brass is near his wife in the church of St Mary Magdalene, Cobham.