Marie-Emmanuelle Bayon Louis (6 June 1745, Marcei – 29 March 1825, Aubevoye) was a French composer, pianist, and salonnière.
Contemporaries credited Mlle Bayon (or Baillon) for making the fortepiano popular in France.
In 1770 she married the architect Victor Louis.
Her surviving works are, as Bayon, a collection of six keyboard sonatas, three of them with violin accompaniment, opus 1 (1769), and, as Louis, the two-act opéra-comique, Fleur d’épine ("May-Flower"), first performed in 1776.
Other works discussed during her lifetime include further instrumental chamber music and opéra-comiques, and music for La fête de Saint Pierre performed in 1771.