Born in Montréal, André Gagnon studied Plastic Arts in Cégep de Joliette between 1980 and 1983. Upon meeting Marc Forest, Benoît Joly, Martin Laplante, Mario Modérie and Marc Pageau, he co-founded the fanzine Opium, where he also published his first works. He went to study Visual Arts and the University of Laval, accompanied by most artists of the Opium group. He was then involved in the the launch of another fanzin, Enfin Bref. He was also active in animation. Gagnon was present in the magazine Safarir from the start in 1987. He created phoney advertisings, caricatures, illustrations, and scenarios, and was editor-in-chief for a while. Gag contributed to Denis Goulet's fanzine ARG and participated in a collective album of Quebecois and Belgian authors. He made his album debut with the commissioned comics 'L'Indésirable' and 'Albert Rouge/Point de Non-Retour'. He created 'Jean Dupays' with Marc Pageau.