Actor who stripped down: Maria Schneider
Why they're fully nude: A relationship based on anonymous sex is bound to have some nudity.
A funny thing happened in Hollywood in the late 1960s and early 1970s: The director became king. Following the success of such counterculture hits as Bonnie & Clyde, The Graduate, Easy Rider, and M*A*S*H, a new generation of kid directors—better known as "The New Hollywood"—took over the power positions previously held by studio heads. They made the rules, had final cut, and no one was about to tell them differently. Not even when it came to gratuitous amounts of carnality.
Like Tropic of Cancer before it (in which an unknown—and uncredited—Ellen Burstyn dons nothing but a come-hither expression), Bernardo Bertolucci's tale of anonymous sex between an American widower (doughy Marlon Brando) and a betrothed Parisian (Maria Schneider) is a testament to the power that filmmakers held in the 1970s, so much so that they could get a major release for an X-rated film.
Though some dismissed the film as nothing more than A-list pornography, the sex in Last Tango in Paris is not without a deeper meaning (albeit a rather nihilistic one). Inspired by Bertolucci's own fleshly fantasies, the film shows that very bad things happen when the veil of anonymity is lifted and a sexual relationship turns personal. When love enters the picture, things can only end badly. At least if you're Brando.