Gus Viseur, born Gustave Joseph Viseur on May 17, 1915, in Lessines, Belgium, was a prominent Belgian/French accordionist known for his contributions to the musette genre and jazz. His father, a bargeman, introduced him to the accordion at the age of eight, and they played together in an amateur band. After his father's death, Viseur performed on the streets of Paris.

In the early 1930s, Viseur played under bandleader Médard Ferrero and began improvising with René "Charley" Bazin, inspired by jazz. He formed his own band in 1935, experimenting with a modern sound by modifying his accordion. Viseur became known for adding swing elements to traditional musette music, notably collaborating with guitarist Baro Ferret. His recording of "L'Accordéoniste" with Édith Piaf in 1940 brought him significant attention.

Viseur toured the United States in 1963, later opening a record shop in Le Havre. He resumed performing around 1970, releasing the album "Swing Accordéon" in 1971. Gus Viseur passed away on August 25, 1974, in Le Havre, France. His representative recordings include "Flambée montalbanaise," "Joseph, Joseph," and "Swing-valse" with Pierre "Baro" Ferret, among others.