Just as there are so many legends about Hanuman, Lord Rama, Shiva, Jesus, Moses and many other great beings.
Of course it depends on each one of us to have or not have faith in these legends and their existence. While their physical representations are ones created by man (perhaps based on what we have seen them to be in our meditations and visions), they allow us to experience them and connect with them through these forms.
Merlin is one such legendary Divine Magician. He calls out to us or comes to us in his own time. Just as is my personal story with Merlin. And when he did call out to me, he began to stir a very sweet magic in my life from the very next day.