Updated: October 18, 2021

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 (1936). 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 (1945).

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 (1951), 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" (1959).

Throughout his career, he made numerous guest appearances on television, particularly on American programs.