After making a name for himself as a director of quality television dramas, Penn made his feature debut with a Western, The Left Handed Gun (1958). A re-telling of the Billy the Kid legend, it was notable for its sharp portrayal of the outlaw (played by Paul Newman) as a psychologically troubled youth (it's telling that the role was originally intended for the archetypal troubled teen James Dean)

Penn's next film was The Miracle Worker (1962), the moving story of Anne Sullivan's struggle to teach the blind and deaf Helen Keller how to communicate. It garnered two Academy Awards.

In 1965 Penn directed the bizarre, surreal Mickey One. Heavily influenced by the French New Wave it was the dream-like story of a stand-up comedian (played by Warren Beatty) on the run from sinister ambiguous forces. Ambitious, startlingly shot and elliptically edited, it baffled critics and audiences alike. Even thirty years on the film has failed to achieve the cult status that some would argue it deserves. It may be worth noting that Mickey One's atmosphere of sweaty paranoia foreshadows some of the conspiracy thrillers of the 70's- not least Warren Beatty's latter Parallax View. (Penn himself later contributed to the genre with Night Moves)

Penn's next film was The Chase (1966) a taut thriller following events in a small civically corrupt Southern town on the day an escaped convict returns (played by Robert Redford). Although not a major success, The Chase nonetheless caught the mood of the turbulent times, a ‘state of the nation' tale of racism, corruption and the violence endemic in American society. The film is also notable for an extended brutally violent scene where Marlon Brando's sheriff is beaten to a bloody pulp- the latest in a long line of masochistic beatings the actor received on-screen in his career (see also One-Eyed Jacks and On the Waterfront).

Re-uniting with Warren Beatty, rural gangster film Bonnie and Clyde (1967) showed that Penn once again had his finger on the pulse of the zeitgeist, perfectly catching the youthful disenchantment of the late 60's. Although depression-set, it was very much in the spirit of the counter-culture. Bonnie and Clyde went on to become a worldwide phenomenon, at the same time (along with Peckinpah's The Wild Bunch a year later) pushing the limits of acceptable screen violence with its bloody machine-gun climax.

Once again the film drew strong influence from the French New Wave and itself went on to make a huge impression on a younger generation of film-makers. Indeed there was a strong resurgence in the “love on the run” sub-genre in the wake of Bonnie and Clyde, most notably Badlands (1973) (where Penn received acknowledgement in the credits).

Next came Alice's Restaurant (1969), based on one of Arlo Guthrie's songs, a satirical account 1960's counter culture. His next film after this was a return to the western, Little Big Man (1970), a shaggy dog story account of one Native American's life (played by Dustin Hoffman). In scale it was Penn's most expansive film to date, an epic blackly comic tale and clearly revisionist in its tone (Little Big Man was one of the many revisionist Westerns released in the late 60's, early 70's).

In 1973 Penn provided a segment for the Olympic film Visions of Eight along with several other major directors such as John Schlesinger and Milos Forman. The directors' next two films showed he had lost none of his ambition (not least in his eclecticism). First came a paranoid LA set thriller, Night Moves (1975) about a private detective (played by Gene Hackman) on the trail of a runaway.

Next came another comic western which reunited him with Marlon Brando, The Missouri Breaks (1976), a ramshackle, eccentric story of horse thief (Jack Nicholson) facing off with an eccentric Irish bounty hunter (Brando). Although receiving mixed reviews at the time, it is held in considerable esteem by many critics now.

Four Friends (1981) was a traumatic look back at the 60's, returning to the old themes of Vietnam, civil rights, sexual politics, and drugs. Perhaps this sense of retrospect was a sign that the director was at last out of touch with the mood of the times. Penn's career subsequently lost its momentum: Target (1985) was a mainstream thriller reuniting the director with Gene Hackman. Dead of Winter (1987) was a horror/thriller in the vein of Alfred Hitchcock.

Since this Penn has returned to work in television, including an executive producer role for popular crime series Law and Order.