The British actor Michael Rennie worked as a car salesman and factory manager before he turned to acting. A meeting with a Gaumont-British casting director led to Rennie's first acting job - that of stand-in for Robert Young in Alfred Hitchcock Secret Agent . He put his film career on hold for a few years to get some acting experience on the stage, working in repertory in York and Windsor. Afterwards, he returned to films and achieved star status in I'll Be Your Sweetheart. In 1951, he was brought to Hollywood by Darrel Zanuck at 20th Century Fox, cast in arguably his most popular role as Klaatu in The Day the Earth Stood Still, now considered a science fiction classic. After that he worked as a supporting actor for eight years until his return to England in 1959. At that time, he took the lead role of Harry Lime in the television series The Third Man. Throughout his career, he made numerous guest appearances on television, particularly on American programs.


Michael Rennie joined the Royal Air Force in 1941, training as a fighter pilot in the United States under the Arnold Plan. While at Napier Field, Dothan, Alabama for his advanced flight training he was asked by fellow trainee, Scotsman Jack Morton, what he did in civilian life. Rennie told Morton and the other pilots gathered around that he was a movie actor. They stared at him in disbelief then broke out in a chorus of laughter. A couple of nights later Rennie and his classmates went into town to watch a movie, "Ships with Wings". Not long into the movie, and much to the surprise of those seated with him, Michael Rennie appeared on the screen as Royal Navy Pilot "Lt. Maxwell" Close friends during his 20th Century-Fox years with Tyrone Power and appeared in a few of his pictures, including The Black Rose and I'll Never Forget You. Graduated from The Leys (a private school in the city of Cambridge). Despite his lean build, he excelled in sports (rowing, fencing, cricket, boxing, wrestling, swimming). Lived his final years in Geneva, Switzerland and died at his mother's home in England while visiting because of his brother's death. In his best known film, the classic sci-fi The Day the Earth Stood Still (1951), a scene was cut that showed his even-tempered alien character Klaatu in an emotional state. His early career was interrupted by war service. He was a flight instructor for over two of those years. His son David Rennie, is now a UK High Court judge on the Lewes, Sussex circuit.