Lagas was the pen name of Belgian comic artist Denis Pierard. He graduated from the Academy of Fine Arts in Liège in 1961 and started his cartooning career as the apprentice of Mittéï for Tintin. Besides several independent gag strips, he also created gags starring the caveman 'Ptyht-Thett' between 1966 and 1969. By 1968 he became a regular in Spirou, creating 'Sam et l'ours' for the magazine's mini-books section with Paul Deliège.