Ever know one of those guys who's always working? Well, if you were able to list their output the same way you could film directors, they would look something like the resumes of these guys. Once the number of movies gets up in the hundreds, it's hard to count because the IMDB starts to list things like participation in documentaries and talk shows, individual TV episodes, uncredited work, etc.. But even if the numbers aren't 100% accurate, the output of these seven filmmakers is indisputable.
1. Steven Spielberg
Love him or hate him, he's an uncanny businessman, a pure entertainer, and a genuine artist with a highly recognizable style (though he rarely transcends the middlebrow), and he has remained relevant for four decades. He has launched or at least aided some interesting careers, most notably Joe Dante (Gremlins), sometimes referred to as the anti-Spielberg, and Robert Zemeckis (Back to the Future, Who Framed Roger Rabbit), who unfortunately went on to make more films. It would take a book to talk in detail about Spielberg's wide-ranging and influential achievements, from "Columbo" to the one-two release of Jurassic Park and Schindler's List in 1993. He's enormously popular, but he has his share of unsung masterpieces that intellectuals can continue to debate and defend. Indeed, in terms of both quantity and quality, I'd argue that few other cinematic legacies come close to this.
Title Count: nearly 500
Essential Films: Raiders of the Lost Ark (1981), Innerspace (1987), Empire of the Sun (1987), Who Framed Roger Rabbit (1988), A.I. Artificial Intelligence (2001)