Midnight Cowboy (1969)
Gross: $45 Million
In the early days of the MPAA system, the "X" rating was meant to imply simply material that was inappropriate for children. It was not until the '70s that it took on the connotation of being strictly for pornography. As such, 1969's gritty look at New York City street hustlers remains the first (and barring a wave of ratings nostalgia, only) X-rated film to win an Oscar for Best Picture.