Ruben Samuel Fleischer (/ˈflaɪʃər/; born October 31, 1974) is an American film director, film producer, television producer, music video director, and commercial director who lives in Montclair, New Jersey. He is best known as the director of Zombieland (2009), his first feature film, and its sequel, Zombieland: Double Tap(2019). He has also directed the films 30 Minutes or Less, Gangster Squad, Uncharted, and 2018's Venom, which features the same Marvel Comics character. Before the features, he directed television commercials for brands like Cisco, Eurostar, ESPN, and Burger King and music videos for artists such as M.I.A., Electric Six, DJ Format and Gold Chains.

Fleischer was born and raised in Washington, D.C, the son of Karen Lee (née Samuel) and David Elliot Fleischer, a physician at the Mayo Clinic in Arizona and a professor of medicine. His brother, Lucas, works in new media. His father was born to a Jewish family, while his mother converted to Judaism. Fleischer was raised in Reform Judaism.