The son of Perceval. According to legend he is summoned from the temple of the Grail at Montsalvatsch and borne in a swanboat to Antwerp. He saves Princess Elsa of Brabant from Frederick of Telramund who wants to marry her against her wishes. Lohengrin will marry Elsa if she does not ask what his race is; but she does, and the swan‐boat carries him back to the Grail castle. The story is the subject of Wagner's opera (1850). In early forms of the legend the Knight of the Swan is called Helias (Helis in Icelandic).