Jean-Émile Diogène Marcoux (June 12, 1877, Turin, Italy – October 22, 1962, Paris, France) was a French operatic bass-baritone, known professionally as Vanni Marcoux (sometimes hyphenated as Vanni-Marcoux). He was particularly associated with the French and Italian repertories. His huge repertoire included an estimated 240 roles and he won renown as one of the most memorable singing-actors of the 20th century.