First Appearance: Doctor Strange, Sorcerer Supreme #61
(referred to) (January 1994).
Appearances: Doctor Strange, Sorcerer Supreme #61 (referred to).
Years Active: 6th Century C.E.? (see below)
Myrrdin is referred to in DSSS #61 by Salome; she claims that she was Sorceress Supreme "before the Ancient One....before green Myrrdin himself." The implication of this statement is that Myrrdin was not only a Sorcerer Supreme, but perhaps the first Earth-born Sorcerer Supreme, or at least the most powerful/famous one.
The historical Myrrdin--yes, there was such a person--was a Welsh bard who is thought to have been the source, here on Earth-Prime, for the legends of Merlin. Some historical records indicate that Myrrdin went insane in 574 during the Battle of Arddeyd and took up residence as a "wild man" in Caledon in south Scotland. How the historical Myrrdin and the Earth-Marvel Myrrdin are related has yet to be revealed, however.