Lohengrin is a character in German Arthurian literature. The son of Parzival (Percival), he is a knight of the Holy Grail sent in a boat pulled by swans to rescue a maiden who can never ask his identity. His story, which first appears in Wolfram von Eschenbach's Parzival, is a version of the Knight of the Swan legend known from a variety of medieval sources. Wolfram's story was expanded in two later romances. Richard Wagner's opera Lohengrin of 1848 is based upon the legend.