Joseph-Ermend Bonnal (1 July 1880 – 14 August 1944); also Ermend-Bonnal, alias Guy Marylis) was a French composer and organist.

He then studied piano at the Conservatoire de Paris under Charles-Wilfrid de Bériot, harmony under Antoine Taudou, composition under Gabriel Fauré and organ under Alexandre Guilmant and Louis Vierne.

He also assisted Charles-Marie Widor at Saint-Sulpice, Albert Périlhou at Saint-Séverin and Charles Tournemire at the Basilica of St. Clotilde.

In 1901, Ermend-Bonnal was appointed Organist at Saint-Médard, and subsequently at Notre Dame in Boulogne-sur-Seine.

However, he also wrote in all other musical genres, ranging from children's pieces for piano to symphonies.