Born and bred in de Veluwe, one of the most conservative regions of Holland, Willem has become one of the world's most unpredictable and sardonic cartoonists. While studying Fine Arts between 1962 and 1967, it all started with some early comix and cartoons for magazines like De Legerkoerier (The Army Courier), and with Willem's contributions to the legendary student magazine Propria Cures. There, he got in touch with Roel van Duyn, the editor of the paper for the hippie movement Provo.
He subsequently became a regular contributor to Hara Kiri as well as its follow-up Charlie Hebdo. Willem's beloved themes such as fat women, biological warfare, crabs, small children and police violence were all represented in the many political cartoons, illustrations, puzzles, comix and texts for the magazine. He also served as a promotor of Dutch comic abroad with his own publication Surprise.
Ever since the late seventies, Willem has been contributing controversial daily cartoons to the French left-wing daily Libération.
Willem was the first Dutch artist to receive the Grand Prix d'Angoulême during the 40th Angoulême Comics Festival in February 2013.