Geoffrey of Monmouth

Geoffrey of Monmouth (c. 1095 – c. 1155) was a clergyman and writer. He was probably born in Wales. He was made the bishop of St Asaph on 21 February 1152.
Around 1136 he wrote "Historia Regum Britanniae " in Latin, translated as "History of the Kings of Britain". It is a mythical history which included the first account of King Arthur, Camelot and the Knights of the Round Table.
Stories about in Geoffrey's book helped to make Arthur a popular character. Shakespeare consulted Geoffrey's book when he wrote "King Lear" and "Cymbeline".
As early as 1190, William of Newburgh wrote "it is quite clear that everything this man wrote about Arthur and his successors, or indeed about his predecessors from Vortigern onwards, was made up, partly by himself and partly by others".