Gélin was born in Angers, Maine-et-Loire into a Jewish family, the son of Yvonne (Le Méner) and Alfred Ernest Joseph Gélin. When he was ten, his family moved to Saint-Malo where Daniel went to college until he was expelled for ‘uncouthness’. His father then found him a job in a shop that sold cans of salted cod. It was seeing the shooting of Marc Allegret’s film Entree des artistes that triggered his desire to go to Paris to train to be an actor. He trained at the Cours Simon in Paris before entering the Conservatoire national d’art dramatique. There he met Louis Jouvet and embarked on a theatrical career. He made his first film appearance in 1940 in Miquette and for several years was an extra or played small roles in French films. He appeared with Jean Gabin and Marlene Dietrich in Martin Roumagnac (1946). He won his first leading role in Rendez-vous de juillet (1949). From that time, he went on to appear in more than 150 films, including Max Ophüls’ films La Ronde (1950) and Le Plaisir (1952), Sacha Guitry’s films Si Versailles m’était conté (Royal Affairs in Versailles) (1954) and Napoléon (1955), Alfred Hitchcock’s The Man Who Knew Too Much (1956), Jean Cocteau’s Le Testament d’Orphée (1960), Le souffle au cœur (Murmur of the Heart) (1971), and La Nuit de Varennes (That Night in Varennes) (1982). While married to Danièle Delorme with whom he had a son, Xavier, he had an affair with model Marie Christine Schneider that produced a daughter, Maria Schneider. However, Gélin refused to acknowledge Maria throughout his life. Gélin also had a daughter, Bénédicte from a later marriage. Gélin died in Paris on November 29, 2002, of kidney failure.