Peter van Diest (1451-1507; latinised as Petrus Diesthemius) was a medieval writer from the Low Countries. The late-15th-century morality play Elckerlijc is attributed to him. Linguist Henri Logeman identified Peter van Diest as Petrus Dorlandus (1451-1507), the vicar of the Carthusian monastery of Diest. Dorlandus also wrote the Corona Cartusiana, a history of the Carthusian order until 1468, and the History of S. Anna (1501). Objections against this identification, however, have been raised. Elckerlijc was translated into English to become the famous Everyman.
