(b Vilnius, Lithuania, 29 Aug. 1896 (some sources say St Petersburg, 31 Aug. 1896); d San Francisco, 15 Aug. 1998)
Russian-US dancer and teacher. He studied at the Imperial Theatre School in St Petersburg, graduating in 1915 into the Mariinsky Theatre and becoming a principal in 1917. In 1921 he and his wife, the ballerina Ludmila Schollar, left Russia and joined Diaghilev's Ballets Russes, where Vilzak danced the role of Prince Charming in Diaghilev's 1921 production of The Sleeping Princess and created roles in Nijinska's Les Biches (1924) and Les Fâcheux (1924). He was the Ballets Russes leading danseur noble, and also in 1923 staged Swan Lake (with Schollar) for the company. In 1925, however, he was dismissed by Diaghilev for supporting the dancers' attempts to gain better working conditions. He subsequently danced for Bronislava Nijinska at the Teatro Colón in Buenos Aires (1926) and joined Ida Rubinstein's company, where he was premier danseur, dancing in the first productions of Nijinska's Les Noces de Psyché et de l'Amour, La Bien-aimée, Baiser de la fée, and Bolero (all 1928) and La Valse (1929), Jooss's Persephone (1934), and Fokine's Diane de Poitiers. He was then ballet master and principal dancer at the State Opera in Riga (1932–4) and in 1932 performed with Théâtre de la Danse Nijinska, creating roles in her Les Comédiens jaloux and Variations. In 1935 he joined the Ballets Russes de Paris and in 1936 René Blum's Ballet Russe de Monte Carlo, where he created the title role in Fokine's Don Juan. He danced in America with Balanchine's American Ballet at the Metropolitan Opera House in New York (1936–7) and in 1940 he began his teaching career in America at the School of American Ballet. He later taught at his own Vilzak-Schollar School in New York (1940–6), the Ballet Russe de Monte Carlo School in New York (1949–51), the American Ballet Theatre School (1951–63), Washington School of Ballet (1963–5), and the San Francisco Ballet School (1965–86). He became one of the most important teachers of the Russian style in America.