Gus Viseur (Gustave-Joseph Viseur, Lessines, Belgium, May 15, 1915 – August 25, 1974, Paris, France) was a Belgian/French button accordionist.
Gus Viseur was a virtuoso in the musette genre, during the swing era in the 1930s. He is the only jazz accordionist who is a member of the famous Hot Club de France, conducted by Charles Delaunay. Gus Viseur began his career playing in the streets of Paris. He managed to get a great sound from a chromatic button accordion. It was clear that he was doing something innovative: He helped create the accordion-jazz style known as manouche.