German theatrical designer who pioneered new techniques in stagecraft with the Wuppertal theatre company from 1953 to 1964 and then with the German Opera on the Rhine, Düsseldorf.

Wendel trained in Bremen, Berlin, and Hamburg and during World War II worked for theatres in Wuppertal and Nürnberg before being appointed head of design in the Württemberg state theatres in 1945. A versatile designer, Wendel brought an original approach to work in drama, ballet, and opera, making particularly novel use of photography and projection in his designs for the 1965 production of Claudio Monteverdi's L'incoronazione di Poppea (“The Coronation of Poppea”) and the 1971 production of Bernd Alois Zimmermann's The Soldiers. His influence on German opera and ballet was at its height during his period in Wuppertal, and his work at numerous foreign festivals ensured his international reputation. Latterly, his designs for Moses and Aaron and Death in Venice were widely praised.