John of Cornwall (or Iohannes Cornubiensis in Latin) was a 12th century Catholic scholar and teacher. He was also known as Johannes de Sancto Germano, from which it is surmised that he was a native of St Germans.
Little is known about his life, but he was living in Paris about 1176. All that is known is contained within a treatise which he wrote, against the doctrine of Abelard. This was entitled “Eulogium ad Alexandrum Papam III, quod Christus sit aliquis homo”, refuting the claim that the humanity of Jesus Christ was purely a garment with which the Logos was clothed.
Various other writings have been attributed to John, without any conclusive evidence. There is no proof that he was the John of Cornwall who was archdeacon of Worcester in 1197. Neither the date of his birth nor that of his death is known.