Jeanne Marie-Madeleine Demessieux (February 13, 1921–November 11, 1968), was a French organist, pianist, composer, and pedagogue.

Jeanne Demessieux was born in Montpellier, in southern France. She was the second child of Marie-Madeleine Mézy and Étienne Demessieux. After taking private piano lessons with her elder sister, Yolande, Jeanne entered the Montpellier Conservatory in 1928. Four years later, in 1932, she obtained first prizes in solfège and piano. In 1933, Jeanne Demessieux was enrolled as student at the Paris Conservatory; studying piano with Simon Riera and Magda Tagliaferro, harmony with Jean Gallon, counterpoint and fugue with Noël Gallon, and composition with Henri Büsser. The same year, she was appointed titular organist at Saint-Esprit (12th arondissement), a post she held for 29 years. Between 1936 and 1939, she studied organ privately with Marcel Dupré, whose organ class at the Conservatoire she joined in 1939. After receiving a first prize in organ performance and improvisation in 1941, Demessieux studied five more years privately with Dupré in Meudon, before she played her début recital at Salle Pleyel in Paris in 1946. This was the beginning of her career as an international recitalist. She played more than 700 concerts in Europe and the United States. Jeanne Demessieux had a prodigious memory: she had memorized more than 2,500 works, including the complete organ works of Johann Sebastian Bach, César Franck, Franz Liszt, Felix Mendelssohn and Marcel Dupré.

Jeanne Demessieux made numerous recordings, including the complete organ works of César Franck, which was awarded the Grand Prix du Disque in 1960.

In 1962, Demessieux was appointed titular organist at La Madeleine in Paris. In addition, she was professor of organ at Nancy Conservatoire (1950–52) and the Conservatoire Royal in Liège, Belgium (1952–68). Owing to health problems, Demessieux was obliged to limit her performance activities during the mid-1960s. In 1967, she signed a contract with the Decca label for a complete recording of Olivier Messiaen's organ works. Owing to her untimely death in 1968 the project was never realized.

Jeanne Demessieux died on November 11, 1968, due to an embolism, in Paris. She left a large catalogue of compositions. Aside from her organ compositions, she wrote pieces for piano, numerous songs and choir works including an oratorio, "Chanson de Roland," and orchestral works. Only one third of her catalogue, which consists of more than 30 compositions, has been published to date.

The Dutch label Festivo has re-released several recordings of Jeanne Demessieux on CD, including her recording of César Franck's complete organ works from 1958.