Il était une fois was a popular French musical group fronted by Joëlle Mogensen as lead vocals. Formed in Paris in 1972, it included besides Mogensen, Serge Koolenn, Richard Dewitte, Lionel Gaillardin, Bruno Walker and Christian Burguière. Walker and Burguière were later replaced by Jean-Louis Dronne and Daniel Schnitzer. The band was signed to the Pathé Marconi label.
The very popular band broke up in 1979 when Joëlle Mogensen left, just three years from her sudden death in 1982 at the age of 29.
The band released 4 studio albums and a great number of singles including "J'ai encore rêvé d'elle" that sold more than 1 million copies. A number of compilation albums have been released later.