In the literature before the 1980s, Merlyn was portrayed as a sorcerer and tutor to a young Arthur.
The name Merlyn or Merlin, stems from the Welsh names Myrddin or Merdin. The Welsh poems dating between the 5th and 8th centuries reference two different characters, one named Myrddin and one named Merdin. Geoffrey of Monmouth combined the two in writing his alleged history of Britain (which is fictional, for more discussion, please see the page).
“The earliest reference to Myrddin comes from the ‘Armes Prydein Vawr’ or ‘Great Prophesy of Britain’ attributed to the sixth century bard Taliesin, but which is not older than 930 AD.” Geoffrey of Monmouth used the poem as one of his sources” (Jones).
Merdin is referenced in the Welsh tale of the concealment of two dragons appears. Merdin was the son of a Welsh king, and had some magical abilities.
In some of the modern re-tellings, in which the magical and fantasy elements have been stripped away, Merlyn was merely a very bright tutor and advisor but did not possess magical abilities.
Jones, Mary. Jones’ Celtic Encylopedia, at http://www.maryjones.us/jce/merlin.html