What opera that Gerd Grochowski performed in was the last of four music dramas?
Gerd Grochowski:  Particularly known for his performances in the operas of Richard Wagner, his roles included Donner in "Das Rheingold", Gunther in "Götterdämmerung", Klingsor in "Parsifal", Kurwenal in "Tristan und Isolde", Telramund in "Lohengrin", and Wotan in "The Ring Cycle".
i don't know