Emmanuel Excoffier, also known as Exem, made his debut in 1983 with several posters. His work is characterized by its sense of composition and its Clear Line style, which is similar to the work of Joost Swarte. Most of his posters and cartoons have been printed in 'Affiches BD, 25 Ans de Création Genevoise', a book compiled by Ariel Herbez and published by Slatkine in cooperation with the Cultural Centre of Saint-Gervais. In 1984 and 1985 he created 'Le Jumeau Maléfique' and 'Zinzin Maître du Monde', two mini-albums parodying the 'Tintin' series by Hergé, published by Éditions Tchang. Exem became known as a miniaturist, and made several commercial books for Belvédaire ('Pas d'Escalade pour le Duc', 'Viva la Musica'), the Red Cross in Geneva ('Le Secret du Pyrophone') and Éditions Minerve ('Rendez-vous avec la Dune').
While pursuing a productive career as an illustrator, Exem has made comics for Tout va bien-Hebdo, Lémaniques and several collective albums. In 1998, he wrote the script for 'Les Héritiers de Sonderbund', a comic drawn by Enrico Marini and published by Suzanne Hurter on the occasion of the 150th anniversary of the federal state of Switzerland. He has also published a couple of books at Drozophile, such as 'Éclats d'Âme' (with Lawrence Suhner).