Merlin is best known as the wizar featured in Arthurian legend. The standard depiction of the character first appears in Geoffrey of Monmouth's Historia Regum Britanniae, and is based on an amalgamation of previous historical and legendary figures. Geoffrey combined existing stories of Myrddin Wyllt (Merlinus Caledonensis), a northern madman with no connection to King Arthur, with tales of Aurelius Ambrosius to form the composite figure he called Merlin Ambrosius.