Kevin McCarthy: Actor best known for his role in the Cold War science-fiction thriller ‘Invasion of the Body Snatchers’

The heavy-set, square-jawed Kevin McCarthy was a distinguished actor with an extensive career in the theatre as well as movies and television, but he will be best remembered for his leading role in one of the most famous of screen science-fiction thrillers, Don Siegel's cult classic, The Invasion of the Body Snatchers (1956), in which he was a doctor desperate to convince the authorities that the human race is being taken over by "pod people".

The Fifties was a particularly productive period for fantasy tales that tapped the paranoia instilled in Americans by Senator Joseph McCarthy's anti-communist hearings and the Korean War, and Invasion of the Body Snatchers is regarded as one of the finest, with a place alongside such classics as The Day The Earth Stood Still (1951), The Thing (1951), Them! (1955) and The Incredible Shrinking Man (1957). A low-budget movie, which was rehearsed for 10 days and had time for few re-takes, it builds suspensefully to the memorable moment when McCarthy rushes into the highway screaming at passing cars and ultimately to the camera (and the audience), "You're in danger... They're here already... You're next! You're next!"

The son of a lawyer, McCarthy was born in Seattle in 1914, but he, his two brothers and his sister Mary (who was to write The Group), were orphaned in the 'flu epidemic of 1918, and they were raised by their paternal grandparents in what Mary described in her memoirs as "near Dickensian mistreatment". After five years, they moved in with their maternal grandfather.

McCarthy was educated at the School of Foreign Service, part of Georgetown University, with ambitions to be a diplomat, then the University of Minnesota, where he first acted. He made his Broadway debut in 1938 playing a small role in Robert E Sherwood's Pulitzer Prize-winning Abe Lincoln in Illinois. He had the role of a rowdy sailor in Mexican Mural (1942), an experimental play about Mexican religious and secular life. It ran for only four performances but introduced McCarthy to Montgomery Clift, who was to become a close friend.

McCarthy had recently married the actress Augusta Dabney, who later recalled, "I look back on the summer of 1942 as the most joyous time of my life." Clift once said that Dabney was the only woman he would consider marrying, but Tennessee Williams commented, "A lot of people in the theatre suspected Monty had actually fallen in love with Kevin and that Kevin was the love of his life."

While serving with the US Air Force during the Second World War, he was one of several future stars to appear in Moss Hart's ambitious drama about young servicemen at flight-training school, Winged Victory (1943). The play had 86 speaking roles, with all the male parts played by servicemen, and McCarthy toured with the show after its successful Broadway run and appeared uncredited in George Cukor's 1944 screen version.

After demobilisation he returned to Broadway, where he was a founding member of the Actors Studio and appeared in Maxwell Anderson's play about returning servicemen, Truckline Café (1946), notable as the play in which Marlon Brando first attracted notice. In 1949 he made his first London appearance, at the Phoenix Theatre playing Biff, the shallow, disillusioned son of salesman Willy Loman (Paul Muni) in Arthur Miller's Pulitzer Prize-winning "tragedy of the little man", Death of a Salesman. McCarthy's performance led to his being cast in the 1951 film version, which won him an Oscar nomination as supporting actor and a Golden Globe as most promising male newcomer.

He returned to Broadway to star in a revival of Anna Christie (1952) and in 1953 he took over the role of Freddie Page in Terence Rattigan's The Deep Blue Sea. He also appeared prolifically on television in such anthology series as Studio One and Playhouse 90.

In 1956 he was given the leading role in Invasion of the Body Snatchers, in which aliens assume the appearance of giant pods as they gradually hatch duplicate humans. Adapted by Daniel Mainwaring and an uncredited Sam Peckinpah from a novel by Jack Finney first published in Colliers magazine, the film was originally intended by Siegel to end with Miles (McCarthy) yelling "They're here already! You're next!" to camera, but the distributors Allied Artists thought it too downbeat and made Siegel add a prologue and a hopeful ending in which a truckload of giant pods is found in a freeway wreck, prompting the FBI to believe Miles.

Siegel removed most of the black humour Peckinpah had put into the script, and gives the film remarkable pace and mounting suspense, culminating in the chilling scene in which Miles and his sweetheart Betty (Dana Wynter), knowing the aliens take over the humans as they sleep, take refuge in a cave where Betty allows herself to fall asleep. Earlier, Miles has joked that he will always know that Betty is Betty by her kiss, and when he kisses her in the cave he recoils in horror as he realises she is a duplicate. When reissued in 1979, the imposed prologue and ending were removed.

The film has been seen as a reaction to McCarthyism, either as a case against the witch-hunts or an allegory about communist infiltration. Siegel and Kevin McCarthy denied these interpretations. "There was no assignment of political points of view," McCarthy said. "People began to think of McCarthyism later. I thought it was about the onset of a kind of life where the corporate people are trying to tell you how to live, what to do, how to behave."

Notable among his other films is the superior film noir, Maxwell Shane's Nightmare (1956), adapted from a short story by Cornell Woolrich, in which he gave a strong performance as a jazz musician who dreams that he stabbed to death a man in a mirrored room, then wakes to find indications that it was not a dream. He made over 50 films, including The Misfits (1961), written by Arthur Miller, in which he played the husband Marilyn Monroe divorces in the opening scene. He initially refused the part, claiming it was too small. "I finally said I would do it if they paid me $100 a word. They said they would. Turns out I had 29 words." He also had good roles in The Prize (1963), playing a Nobel prize-winner for medicine who becomes embroiled in a criminal plot, The Best Man (1964), a gripping adaptation of Gore Vidal's tale of political manoeuvring, and Edward Dmytryk's convoluted mystery, Mirage (1965).

In 1976 he played a cameo role in the remake of Body Snatchers, but he had more challenging opportunities in the theatre. In 1959 he took over from Henry Fonda on Broadway in Two for the Seesaw, a play he would frequently return to for touring productions. In Advise and Consent (1960) he was chilling as a ruthless, power-hungry politician who blackmails a colleague about a homosexual incident, and he also starred in Brecht on Brecht (1963) and played Vershinin in The Three Sisters (1964). For over 20 years he toured in a one-man show, Give 'Em Hell, Harry, giving a many-faceted performance as President Harry Truman (McCarthy was a distant cousin of the US senator and presidential candidate Eugene McCarthy). In recent years a frequent presence at science-fiction fairs and movie conventions, he said he had no intention of retiring ("I love to work. I love to be in things."), and he appeared this year in a short film, Drawback.

In 2008 the American Film Institute named Invasion of the Body Snatchers one of the top 10 science fiction movies of all time. "I must say," said McCarthy, "I'm enthralled by the power of the picture all over the world... the toasts just keep coming my way."

Kevin McCarthy, actor: born: Seattle, Washington 15 February 1914; married: 1941 Augusta Dabney (divorced 1961; three children), 1979 Kate Crane (two children); died Hyannis Port, Massachusetts 11 September 2010.