Upon graduating from high school in New Jersey, Nicholson visited Los Angeles, where June had relocated, and remained after getting a job as an office boy in MGM's cartoon department. He drifted into Jeff Corey's renowned acting class, meeting, among others, Towne. His work in low-budget films placed him in collaborations with the likes of Monte Hellman, Bob Rafelson and Corman who directed him in three early horror films ("The Little Shop of Horrors" 1961, "The Raven" 1963 and "The Terror" 1963). Boredom with acting led to his first screenwriting credit, shared with Don Devlin, on Jack Leewood's political thriller "Thunder Island" (1963), a project in which he did not act. Nicholson and Hellman both (along with Francis Ford Coppola) provided Corman uncredited directorial assistance on "The Terror". Nicholson then acted in Hellman's "Back Door to Hell" (1964) and "Flight to Fury" (1966), which he also scripted, before journeying to the Utah desert to make back-to-back films, Hellman's existential Westerns "The Shooting" (1966) and "Ride the Whirlwind" (1966).

Nicholson was Hellman's closest ally during that productive foray, co-producing both movies, playing the gunman Billy Spear in "The Shooting" and scripting and acting in "Ride the Whirlwind.” He wrote Corman's "The Trip" (1967), a definite period piece about a commercial director who ingests LSD, and along with its first-time director Rafelson, co-wrote "Head" (1968), a plotless but visually interesting feature headlined by The Monkees. The actor campaigned for the part abandoned by Rip Torn that would capture the attention of Hollywood and earn him a Best Supporting Actor Oscar nomination. This breakthrough role in the cult hit "Easy Rider" (1969) introduced Nicholson to millions unfamiliar with his work. As the dissipated Southern lawyer who finds a temporary kind of freedom on the road with two long-haired bikers, he established an instant rapport with both male and female filmgoers. Largely cut from Vincent Minnelli's "On a Clear Day You Can See Forever" (1970), he reunited with Rafelson for "Five Easy Pieces" (1970) and further established his star with his portrayal of a rebellious soul sending out cries of distress about the banality of a life pursued without artistic ambition or love. Nicholson's naturalistic performance, with its minimal gestures and occasional explosions of temper, seemed to re-define screen cynicism for the decade and garnered him another Oscar nomination, this time as Best Actor.

The 1970s offered Nicholson at his very best, a nuanced performer mastering his appearance from film to film so that he never quite seemed the same. The wavy hair of "Five Easy Pieces" gave way to the middle-aged thinning of "The King of Marvin Gardens (1972), then the crew cut of "The Last Detail" (1973) and the central parting of "Chinatown" (1974), but always underneath was the droll, bleakly cheerful, enigmatic Nicholson refining his style so long unobserved during the 60s. Mike Nichols gave him a chance to play a role that resonated his own life: the compulsive misogynistic stud Jonathon in "Carnal Knowledge" (1971). Though the part allowed the actor to display considerable range, Nichols may have erred in not exploring the roots of his lead character's behavior. Rafelson's "The King of Marvin Gardens" presented him as a shy intellectual who escapes his staid reserve via the expansive fantasy of his late-night radio show but fails to discourage his rambunctious con man brother (Bruce Dern) from his outlandish financial schemes. Hal Ashby's "The Last Detail" cast him as the Shore Patrol wise-ass Buddusky, given to quoting Camus and Nietzsche, who sets the leisurely pace for escorting (along with Otis Smith) Randy Quaid to a Navy prison. The essence of the Robert Towne adaptation of Darryl Ponicsan's novel was the exchange of compassion between the guards and prisoner, and Nicholson's outstanding performance earned him another nomination for the Best Actor Oscar, inching him a step closer to possessing a statue of his own.

Roman Polanski's "Chinatown" provided Nicholson with perhaps his greatest screen role as Chandleresque gumshoe Jake Gittes, a part he would reprise in the inferior sequel "The Two Jakes" (1990). Written for him by longtime friend Towne, the Gittes character incorporated the collective Nicholson persona to that date elevated to a fever pitch, allowing Polanski to use him as the straw to stir a very heady mix including John Huston, in addition to Dunaway. The fact that Nicholson had recently begun seeing Huston's daughter Anjelica added subtextual menace when the old man (as Noah Cross) ominously slurred, "Are you sleeping with her?" A spicy combination of fact and fiction, "Chinatown" recalled the swindles and corruption that helped transform small town L.A. to the metropolis it is today. This complex, literate, sensual and sentimental movie has deservedly found its way onto many lists of the ten best films ever, making it an impossible act for "The Two Jakes" to follow. Though not honored by the Academy for Gittes, Nicholson finally won a Best Actor Oscar for his portrayal of Randall P McMurphy in Milos Forman's superb ensemble showcase "One Flew Over the Cuckoo's Nest" (1975), which posed the familiar question "Who's more insane, the keepers or the kept?". McMurphy attacked the institution's establishment, sacrificing himself in the end so that others (particularly the Chief) can become "whole" again. Earlier that year, Michelangelo Antonioni's "The Passenger", his only European movie, had provided him an opportunity to bring his personal flair to the role of an alienated American journalist.

As the 70s came to an end, Nicholson began abandoning his more subtle shadings for over-the top hamminess and, at worst, self-parody. Still, buried beneath the excess, one could always find signs of the stuff that had made him a great film actor. He teamed with Marlon Brando, also suffering from the same malady, for the disastrous "Missouri Breaks" (1976), and with Stanley Kubrick's big-profile "The Shining" (1980) kicked off the 80s, inaugurating caricature as the distinguishing mark of the "new" Nicholson. The mugging continued, eyebrows arching ever higher, as the simpleminded, selfish murderer in Rafelson's disappointing "The Postman Always Rings Twice" (1981), the over-praised, dimwitted Godfather impersonation in Huston's "Prizzi's Honor" (1985) and the horny little designer-clad Devil in "The Witches of Eastwick" (1987). His best work of the decade was undoubtedly as Eugene O'Neill in Warren Beatty's epic "Reds" (1991) and in James L Brooks' "Terms of Endearment" (1983). For his boozy ex-astronaut Garrett Breedlove in the latter, Nicholson once again got in touch with his honesty, accentuating his belly as a symbol of Everyman humanity, and delivered the kind of performance that had catapulted him to stardom, earning his second Oscar as the year's Best Supporting Actor.

Tim Burton's "Batman" (1990) introduced Nicholson as consumer icon, thanks to the lucrative back-end deal which earned him a reported $20 million from merchandising profits, plus additional moneys from the sequel, "Batman Returns" (1992), in which he didn't even act. Nicholson's Joker dominated the movie, its broad cartoon canvas the perfect backdrop for his perpetually posturing and leering psychotic villain. He was top-notch as the commanding officer who does not want the truth told in Rob Reiner's "A Few Good Men" and Danny De Vito's "Hoffa" (both 1992) provided a vehicle in which he was once again larger than the movie. His turn as a book editor who gradually evolves into a werewolf in Mike Nichols' "Wolf" (1994) served as a metaphor for confronting mid-life crises. At the start of the film, before the wolf bites him, he is weak-willed and passive, but his transformation into the wolfman brings virility and growing confidence. Not surprisingly, Nicholson called into play many of his trademark mannerisms, offering a wry, sly commentary on his star power, proving once again there was no limit to how long he could get away with such hokum.

In Sean Penn's "The Crossing Guard" (1995), Nicholson once again essayed a bitter man confronting the wounds of the past. As a jeweler whose daughter had been killed by a hit-and-run driver, he delivered a nuanced portrait that was equal parts guilt and grief, the scenes shared with real-life former lover Anjelica Huston (as his ex-wife) mined an understandably rich vein of remembered feeling. 1996 found him reprising his Oscar-winning turn as Garrett Breedlove opposite Shirley MacLaine in "Evening Star" and playing the dual role of the US President and a sleazy Las Vegas promoter in Tim Burton's "Mars Attacks!", its cheesy comedy perfect for the broad strokes of the Nicholson caricature. He reunited with Rafelson for the thriller "Blood and Wine" (1997), and though it did not misfire as badly as his earlier comedy "Man Trouble" (1992), which had also employed writer Carole Eastman in an attempt to repeat their success of "Five Easy Pieces", it did not do well at the box office either. Nicholson then reunited with James L Brooks in an Oscar-winning turn as a curmudgeonly, homophobic writer who falls for single parent Helen Hunt and comes in contact with gay artist Greg Kinnear in "As Good as It Gets" (1997).

After a three year hiatus, Nicholson returned to the big screen as Jerry Black in the thriller feature "The Pledge," another harrowing directorial effort from his friend Sean Penn, a performance that was widely hailed in an otherwise bleak film. In 2002 Nicholson made another comeback, teaming with writer-director Alexander Payne for "About Schmidt," an introspective, serio-comic story about Warren Schmidt, an unhappy retired salesman reflecting on his life, making a cross country trek to attend the wedding of his estranged daughter after the death of his wife . His fresh, unexpected performance was rewarded with several award nominations and trophies, including the Golden Globe for Best Actor in a Motion Picture Drama and an Academy Award nomination for Best Actor, the actor's twelfth nomination, breaking his own record as the most nominated male actor in Oscar history.

In addition to acting Nicholson has worked as a director three times, first on "Drive, He Said" (1971), which he also co-wrote, a flawed personal study of alienated youth within the rigid environment of an athlete-oriented college. A commercial failure (though a sensation at Cannes), it starred Bruce Dern as a gung-ho basketball coach and has survived better than many period pieces of the time (i.e., "The Strawberry Statement"). Nicholson the director let Nicholson the actor totally off the leash in "Goin' South" (1978), yet his unchecked mayhem did not totally destroy this amusing off-beat Western, most notable for the film debuts of John Belushi and Mary Steenburgen. Finally, he brought in the troubled "The Two Jakes" on time and under budget, but no amount of tweaking by screenwriter Towne could have resolved the muddle of a script that was confusing even to audiences familiar with "Chinatown". In a town where friendships are fleeting, Nicholson has a reputation for fierce loyalty, particularly to the people he knew before he was a household name, but the complications that delayed "The Two Jakes" for five years may have done irreparable damage to his relationship with Towne, the film's original director whom Nicholson replaced.

As a writer, Nicholson has received and/or shared screenplay credit on various films, including the low-budget "Thunder Island" and "Ride in the Whirlwind" and "Flight to Fury." He also was a writer on the psychedelic '60s film "The Trip" and the Monkees' offbeat screen outing "Head." Among more serious fare, he adapted Jeremy Larner's book "Drive, He Said" and shared screenplay credit with Adam Sandler, Tim Hurlihy and David Dorfman for "Anger Management."

Balancing his penchant for top-level acting with a bid for another major commercial success, Nicholson next teamed with popular comedy star Adam Sandler for "Anger Management" (2003), with both stars contributing to the screenplay. Taking his charismatic devilishness into uncharted territory, Nicholson played an unconventional anger management therapist who exacerbates, rather than cures, the rage of his patient, Sandler. The actor then took on another late-career-defining role when he starred opposite Diane Keaton in the romantic comedy "Something's Got to Give" (2003) playing an aging womanizer with a penchant for much-younger women who surprises himself by taking up with the mother (Keaton) of one of his beautiful dates (Amanda Peet) after being laid up following a heart attack in her beach house. Although the film was uneven in the early and late stretches, at the heart of the story Nicholson and Keaton displayed a remarkable romantic chemistry buoyed by comedic frisson, making for a crowd-pleasing hit that earned the actor yet another Golden Globe nomination for Best Performance by an Actor in a Motion Picture Musical or Comedy.