Jef Mertens was born on April 27, 1874 in Leuven, Flanders, Belgium as Joseph Marie François Mertens. He was an actor and director, known for Jopie Gaat Trouwen (1912), Roze Kate (1912) and De bannelingen (1911). He was married to Cato Mertens-de Jaeger. He died on July 15, 1929 in The Hague, Zuid-Holland, Netherlands.