Mississippi Mermaid (French: La sirène du Mississipi) (1969) is a French film directed by François Truffaut. The film is adapted from the 1947 William Irish (Cornell Woolrich) novel Waltz into Darkness. The film features Jean-Paul Belmondo, Catherine Deneuve, and others. The film had a total of 1,221,027 admissions in France.

It was remade in 2001 as Original Sin, starring Antonio Banderas, Angelina Jolie, Thomas Jane, and directed by Michael Cristofer.