While enrolled in the pre-med program at Berkeley, Big took a trip to New York City, where he saw Vera Zorina in "I Married an Angel", and changed his priorities, withdrawing from medicine and joining a small theater group on campus. After returning to NYC in 1939, he won a scholarship to the prestigious Neighborhood Playhouse School of Dramatics, and his acting career took off. The plays in which he appeared ("Morning Star," "The Willow and I," "Sons and Soldiers") were less than successful, but Peck's excellent notices attracted the attention of Hollywood. The scarcity of leading men during the war years (Peck was exempt from service because of a spinal injury), the glowing reviews of his Broadway performances and savvy manipulation on the part of his agent, Leland Hayward, all contributed to Peck's being in great demand. In fact, the young actor soon found himself starting his Hollywood career under contract to four studios: RKO, 20th Century-Fox, Selznick Productions and MGM.

His first film, "Days of Glory" (1944), an over-ripe tribute to Russian peasant resistance against the Nazis, featured Peck as a strong-boned resistance leader, but it was "The Keys of the Kingdom" (1945) with Peck as a dedicated Roman Catholic missionary to China, that made him a star. This was the first of his incarnations as an authority figure of quiet dignity and uncompromising single-mindedness. The next four decades saw him play variations of that character in "The Yearling" (1946), "The Macomber Affair" (1947), "The Gunfighter" (1950), "The Man in the Gray Flannel Suit" (1956), "The Guns of Navarone" (1961), "The Omen" (1976) and "Old Gringo" (1989), among many others. During the 50s in particular, Peck embodied a certain Everyman as hero, and he managed to be relaxed in the part whether it was his business executive in "Gray Flannel" or in his occasional comedies, "Roman Holiday" (1953) being the most successful film to tap into the unexpectedly lighthearted aspects of his screen persona.

Interspersed among these films were others depicting a darker side to his persona, a man fatalistically obsessed (even possessed) by hidden demons that push him toward the brink of madness. Hitchcock's "Spellbound" (1945), with Peck as an amnesiac who may have committed a murder, was the first to exploit his image in this way. He was Lionel Barrymore's evil son in "Duel in the Sun" (1947), seducing the beautiful Jennifer Jonesbut refusing to take her as his wife, despite killing in cold blood over her. "Yellow Sky" (1948) pitted him as an outlaw head of a gang of thieves against the mysterious Anne Baxter who matched him stride for dramatic stride. He succumbed to his demons, cracking under the strain of command in the marvelous "Twelve O'Clock High" (1949), and there was his maniacal obsession as Captain Ahab, relentlessly pursuing the great white whale "Moby Dick" (1956). He saved his most despicable part, that of Dr. Joseph Mengele in "The Boys of Brazil" (1978), for late in his career, jumping at the chance to work with Laurence Olivier, despite alienating some of his fans.

A lifelong Democrat, Peck acquired the reputation as Hollywood's house liberal, a fact which earned him a spot on fellow Californian Richard Nixon's infamous enemies list and later made him Ronald Reagan's "former friend." In the movies, he was the same kind of activist as in real life, garnering his third Best Actor Oscar nomination as the writer who pretended to be Jewish to expose anti-Semitism in Elia Kazan's "Gentleman's Agreement" (1947). He won his Academy Award for "To Kill A Mockingbird" (1962), portraying Atticus Finch, a small-town, color-blind Southern lawyer whose quiet intensity and moral courage summarized Peck's screen persona. ("It'll be the first line in my obituary, and that's all right with me," he told NEWSDAY, February 27, 1997) He also appeared in Stanley Kramer's "On the Beach" (1959), with its strong message that man could destroy the earth through nuclear war, battled stodgy bureaucracy and macho military mentality as an army psychiatrist in "Captain Newman, M.D." (1963) and portrayed war hero "MacArthur" (1977) as well as a priest saving Jews in World War II in the CBS-movie "The Scarlet and the Black" (1983) and a cameo as the US President in the anti-nuclear film, "Amazing Grace and Chuck" (1987).

Peck enjoyed a successful producing career beginning with William Wyler's "The Big Country" (1958), a Western in which he starred as an ex-sea captain forced to take sides in battle against Burl Ives and sons over water rights. He followed with "Pork Chop Hill" (1959), an uncompromising war film that was almost documentary-like in its story of men dying for a worthless hill in Korea. Though that film failed to attract much of an audience, his next producing effort "Cape Fear" (1962) registered with fans and inspired the 1991 Martin Scorseseremake featuring a cameo by Peck, the last time (to date) his image has graced the silver screen. He also produced two features in which he did not act, "The Trial of the Catonsville Nine" (1972) and The Dove" (1974). He also executive produced TNT's "The Portrait" (1993), an adaptation of Tina Howe's play "Painting Churches" directed by Arthur Penn. In his last starring vehicle to date, Peck played an aging poet opposite Lauren Bacall as his wife and real-life daughter Cecilia as his painter daughter.

As his film career wound down, his philanthropic efforts in support of arts organizations flowered, with Peck working tirelessly as a founder of the American Film Institute, three-term president of the Academy of Motion Picture Arts and Sciences and member of the National Council of Arts, making him seem less an actor than a politician. As such, it seemed fitting that the two Pecks finally melded when he was cast in his first dramatic TV role, that of Abraham Lincoln in the 1982 CBS miniseries "The Blue and the Grey" (CBS). While still in good health into his 80s, he scorned the kind of grandfatherly roles coming his way but did not rule out a return to the big screen if the right project materialized. Having played Starbuck in a college production of Melville's epic and bedeviled the great white whale as Ahab in the 1956 feature, he couldn't pass up the opportunity to act a third time in "Moby Dick", earning an Emmy nomination for his turn as the fire-and-brimstone preacher (played by Orson Welles in the movie) in the 1998 USA Network miniseries version. If he never stepped before the cameras again, that was a suitable bookend to a glorious career.