Although he was born in Belgium, Gérard Lemaire spent sixteen years of his childhood in Africa. Back in Belgium at age 18, he started his artistic education at the Académie Royale des Beaux-arts in Brussels. He met Jean Graton, whom he assisted on the backgrounds of 'Michel Vaillant' for a year. He assumed the pseudonym Gelem and joined the magazine Spirou in 1968. He made several "mini-books" and short stories with characters like 'Tom Bolah', 'Bidule' and 'Ted et Narcisse' for the magazine. He also made 'Tof et Popol' in Le Soir, as well as several illustrations and caricatures in other magazines.
He became head of the Publi-Market agency in 1979, and put his comics career on hold. In 1985, he returned to Spirou, this time under the pseudonym Glem. He started out with some short stories of 'Freddy Guidon' scripted by Thierry Groensteen, but eventually took on the gag series 'Les Voraces' with writer Raoul Cauvin. 'Les Voraces' ran until 1996 and several albums have been published. In addition, with scriptwriter François Gilson, Glem made 'Non Sense' in 1992 and 1993, followed by 'Enzo et les Zootres' six years later. Besides his occasional appearances in the comics scene, Lemaire is mostly active as a freelance advertising artist.