You know, if it wasn't Merlin, it could have been Arthur.
But if it wasn't either of them, (likely, since I recall that Shakespeare was only a few hundred years ago), it could have been Shakespeare himself…but nah, it could (and probably is), somebody else.
And Maeve wasn't of either of these, as I recall per WoG that it was an Austrian Composer, which means it was possibly Beethoven or Mozart.