Sergey Yurievich Sudeikin, also known as Serge Soudeikine (19 March 1882 in Saint Petersburg – 12 August 1946 in Nyack, New York), was a Russian artist and set-designer associated with the Ballets Russes and the Metropolitan Opera.
Having been banned from the Moscow School of Painting, Sculpture and Architecture for his "obscene drawings", Sudeikin joined the Mir Iskusstva movement.
His close friends included the poet Mikhail Kuzmin and the impresario Serge Diaghilev, at whose invitation he came to Paris in 1906 for the Salon d'Automne Exhibition, where his work was first shown abroad.
From 1907 to 1918 he was married to actress Olga Glebova (1885–1945), one of the famed beauties of St Petersburg and the closest friend of Anna Akhmatova.
In 1913 he had eloped to Paris with the dancer Vera de Bosset, whom he subsequently married, and who in the 1920s left him to become the mistress and ultimately second wife of Stravinsky.