Interesting note - the Walkers in Mists, which he was one of, call their elected Chief Druid "The Merlin" - the current Merlin is the 1e signature character Morvran. If Myrddin created the Legacy then it's possible the position is named after him, but as he was a post-Roman tension-between-Asatru-and-Christians kind of guy, the druidic heritage he belonged to likely existed waaaaaay before him - the reason his Wending has entrances in North Wales is because the Isle of Mona is a short swim away, after all.

Anyways. "Emrys" was probably his Shadow name, and Myrddin...