Lohengrin

Lohengrin in British fable, was the famous guard and protector of the sacred Graal. He saved Elsa, the princess of Brabant, from a magician, by coming to her as a swan. She married the valiant knight, but on condition that she would not inquire as to his ancestry. Finally she asked about this, and Lohengrin fled on his swan back to the sacred Graal.