Alec McCowen was born Alexander Duncan McCowan on May 26, 1925 in Tunbridge Wells, England. After studying at the Royal Academy of Dramatic Art, he made his professional debut in 1942. He established his reputation in classical stage roles, appearing in the ensemble of Laurence Olivier's famed duo-production of William Shakespeare's "Anthony and Cleopatra" and George Bernard Shaw's "Caesar and Cleopatra" at the 1951 Festival of Britain. McCowen transferred with the productions to New York that same year, making his Broadway debut.

McCowen made his movie debut in The Cruel Sea (1953), but for his turn as Police Inspector Oxford in Alfred Hitchcock's Frenzy (1972), his reputation is rooted in his stage work. "Frenzy" led to his one lead role in a major motion picture, that of Henry Pulling in George Cukor's adaptation of 'Graham Greene's Travels with My Aunt (1972). Though the film won an Oscar for Costume Design and a Best Actress nod for co-star Maggie Smith (among its total of four nominations), the movie did not advance McCowen's career. Over a decade later, he played the title role in the Thames Television series Mr. Palfrey of Westminster (1984), which ran for two seasons on British television from 1984 to 1985. His last cinema appearance was in a small role in Gangs of New York (2002) for director Martin Scorsese; he had earlier appeared in Scorsese's The Age of Innocence (1993).

Though his services were in demand in movies and on television, McCowen remained wedded to the stage; he regards the character of "Astrov" in Anton Chekhov's "Uncle Vanya" as his favorite role. From 1967 to 1992, McCowen appeared nine times on Broadway, for which he garnered two Drama Desk Awards (out of four nominations) and three Tony Award nominations. One of his Tony Award nominations was for his magisterial solo performance in "St. Mark's Gospel", which debuted on Broadway in 1978 and had a return engagement on the Great White Way in 1981.

He was appointed Officer of the Order of the British Empire (OBE) in the 1972 Queen's New Years Honours and Commander of the Order of the British Empire (CBE) in the 1986 Queen's New Years Honours for his services to drama. Alec McCowan died at age 91 on February 6, 2017 in London, England.