Marie-Louise Pleiss, stage name Ria Bartok (28 January 1943 Einbeck, Germany – 2 March 1970 Paris), was a French singer of yéyé pop songs.
She saw her first success at the age of 20 with the song "Parce que j'ai revu François".
Part of the yéyé wave of the 1960s, she faced difficulty making herself known to the public at large.
She was overshadowed by other singers of her generation such as Johnny Hallyday, Sylvie Vartan, and Richard Anthony.
Bartok nevertheless saw her greatest success with the song "Et quelque chose me dit".