Geoffrey of Monmouth (Latin: Galfridus Monemutensis, Galfridus Arturus; Welsh: Gruffudd ap Arthur, Sieffre o Fynwy; c. 1095 – c. 1155) was a Christian cleric from Monmouth, Wales, and one of the major figures in the popularity of tales of King Arthur. He is best known for his chronicle The History of the Kings of Britain (Latin: De gestis Britonum or Historia Regum Britanniae) which was widely popular in its day, being translated into other languages from its original Latin. It was given historical credence well into the 16th century, but is now considered historically unreliable.

Key figuresGeoffrey of Monmouth