Lucas Belvaux (born 14 November 1961 in Namur, Belgium) is a Belgian actor and film director. His directing credits include the Trilogie, consisting of three films with interlocking stories and characters, each of which was filmed in a different genre. The three films are Cavale, a thriller; Un couple épatant, a comedy; and Après la vie, a melodrama. The Trilogie received the André Cavens Award. His film La Raison du plus faible was entered into the 2006 Cannes Film Festival. His film One Night (38 témoins) was nominated for seven Magritte Awards, winning Best Screenplay.
He also appeared as an actor in the film Merry Christmas (2005). He is the brother of Rémy Belvaux and Bruno Belvaux.