Jean-Émile Diogène Marcoux (12 June 1877 – 22 October 1962) 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.