Actor Robert Vaughn, star of the 1960s TV series "The Man from U.N.C.L.E." (AP/AP)

Robert Vaughn, an Oscar-nominated actor who portrayed a suave spy in the 1960s television series “The Man From U.N.C.L.E.” and who had a secondary career as a political activist and scholar of writers and actors blacklisted as a result of the midcentury communist scare, died Nov. 11 at a hospice facility in Danbury, Conn. He was 83.

The cause was acute leukemia, said his manager, Matthew Sullivan.

From 1964 to 1968, Mr. Vaughn was one of the most recognizable stars in Hollywood, playing Napoleon Solo in the NBC spy spoof “The Man from U.N.C.L.E.” The character was developed by Ian Fleming, the creator of James Bond, as something of a small-screen Bond.

Darkly handsome, with a prominent chin and a distinctive, cultivated voice, Mr. Vaughn starred alongside David McCallum, playing the Russian spy Illya Kuryakin. Together, they were an international crime-fighting duo defying Cold War convention in a tongue-in-cheek series that was one of the most popular shows of its time.

Each week, the pair from the United Network Command for Law and Enforcement, a private organization “involved in maintaining political and legal order anywhere in the world,” accepted a mission from their boss, played by Leo G. Carroll. With wit and panache, they overcame the deadly gadgets and thugs put in their way by their nemesis, THRUSH — while finding time to romance glamorous women.

Actor Robert Vaughn. (Anonymous/AP)

No matter how perilous their travails, they always managed to escape with their well-fitted suits, stylish hair and debonair manner intact.

“There was something cool about it,” Ron Simon, curator of television and radio at the Paley Center for Media in New York, told the Los Angeles Times last year. “It created an emotional resonance for TV. It became the most popular show on campus in 1964, ’65 and ’66 — the first two seasons. It was a cultural phenomenon.”

Mr. Vaughn and McCallum had a genial screen chemistry, trading quips and maintaining a blithe sang-froid in the face of danger. They received thousands of letters a week from fans, and when the Beatles came to the United States in 1966, they asked to meet Mr. Vaughn.

Throughout a six-decade acting career, Mr. Vaughn appeared in more than 100 films and as many television productions. In his early years in Hollywood, he was known as a man about town, often dating beautiful actresses (including Natalie Wood) and indulging in revelry with actor friends, including Steve McQueen, James Coburn and Richard Harris.

In 1959, he played opposite Paul Newman in “The Young Philadelphians,” a film about upper-class hypocrisy. He portrayed a ne’er-do-well from a wealthy family who loses an arm in the Korean War, becomes an alcoholic and later stands trial for murder. Mr. Vaughn was nominated for an Academy Award as best supporting actor but lost to Hugh Griffith from “Ben Hur.”

Mr. Vaughn was the last surviving principal actor from the classic 1960 western “The Magnificent Seven,” in which he played a reluctant gunfighter alongside Yul Brynner, Charles Bronson, Coburn and McQueen. He and McQueen were reunited in the 1968 drama “Bullitt,” in which Mr. Vaughn played a corrupt politician. The film, which starred McQueen as a rogue police officer and featured one of the great car chases in cinematic history, was a box-office success.

Beyond his acting, Mr. Vaughn had a serious side and was an engaged political activist throughout his career. He was a friend of Robert F. Kennedy and in 1966 took an early stance against U.S. involvement in Vietnam. He often spoke on college campuses and, on separate occasions, debated the Vietnam War with Vice President Hubert H. Humphrey and conservative writer William F. Buckley Jr. on Buckley’s “Firing Line” TV program.

Robert Vaughn with his Emmy Award for outstanding supporting actor for "Washington: Behind Closed Doors." 1979 photo. (AP/AP)

While making “The Man From U.N.C.L.E.,” Mr. Vaughn took graduate courses at the University of Southern California, from which he received a doctorate in mass communications in 1970. His dissertation, about the chilling effects of the House Un-American Activities Committee on the theatrical world and Hollywood, was revised and published as a book, “Only Victims: A Study of Show Business Blacklisting,” in 1972. It is still in print.

“Probably the greatest harm done to the theater,” Mr. Vaughn said in 1972, “was in an area that you cannot easily document — that is the words that were not written through intimidation and fear of future investigations. The committee’s methods and procedures silenced perhaps a generation of writers who might have contributed bounteously to a healthy theater in a democratic society.”

Robert Francis Vaughn was born Nov. 22, 1932, in New York City. Both of his parents were actors, but they separated when he was an infant. He grew up with his grandparents in Minneapolis.

He occasionally appeared in radio serials as a child and began acting in stage plays at 12. In 1956, he received a bachelor’s degree in theater arts from what is now California State University at Los Angeles. He received a master’s degree in the same field in 1960 from USC and was an early acting teacher of Jack Nicholson’s.

Mr. Vaughn served in the Army and had a few small film roles before he was cast in “The Young Philadelphians.” A major role in the short-lived TV military drama “The Lieutenant” led to his star turn in “The Man From U.N.C.L.E.”

He appeared in the 1969 World War II film “The Bridge at Remagen” before returning to television in 1972 in “The Protectors,” a detective show produced in England. He often acted in miniseries in the 1970s, including the political drama “Washington: Behind Closed Doors” (1977), for which he won an Emmy Award for best supporting actor. He received another Emmy nomination for his portrayal of President Woodrow Wilson in “Backstairs at the White House” in 1979.

Mr. Vaughn played four other presidents in various stage and television productions — Richard M. Nixon, Harry S. Truman, Theodore Roosevelt and Franklin D. Roosevelt. Over the years, he had recurring roles in several TV series and was in such films as “The Towering Inferno,” “Superman III” and “Delta Force.” He also appeared in many theatrical productions, including A.R. Gurney’s “Love Letters” with Polly Bergen on Broadway in 1990.

From 2004 to 2012, Mr. Vaughn starred in the popular British TV series “Hustle,” playing an aging mentor to a group of con artists. He published a memoir, “A Fortunate Life,” in 2008 and appeared in a London production of the play “Twelve Angry Men” from 2013 to 2015.

Survivors include his wife of 42 years, Linda Staab Vaughn of Ridgefield, Conn.; two children; and two grandchildren.

While filming “The Magnificent Seven” in Mexico, Mr. Vaughn and McQueen had a near-disastrous evening at a brothel. They had no cash, and the establishment refused to accept McQueen’s Diners Club card.

“We just ran,” Mr. Vaughn recalled in a 2015 interview with the Irish Mirror. “I jumped out the window and ended up climbing over a wall, and as I dropped down on to a street, I thought, ‘This is the end for me.’ ”