Walter Nouvel, called "Valitchka", was a Russian émigré art-lover, amateur musician, music critic, and writer. Nouvel fled the Soviet Union in 1919 and worked as secretary and factotum for Diaghilev's Ballets Russes. He wrote music critics for Diaghilev's Mir iskusstva journal, and was de facto administrator of Ballets Russes.

He was a life-long friend of Serge Pavlovitch Diaghilev. He co-wrote with Arnold Haskell a biography of Sergei Diaghilev (Diaghileff. His Artistic and Private life).