Mary Tamm (22 March 1950 – 26 July 2012) was a British actress who appeared in many British TV drama series and serials. She is best known for her role as Romana I in the BBC's science fiction television series Doctor Who, appearing opposite Tom Baker in the 1978–1979 story arc The Key to Time.

Tamm was born in Bradford, West Riding of Yorkshire, to an Estonian father and a half-Russian mother, who was an opera singer. Her parents had fled Estonia after four of her father's brothers had died in Stalin's gulag labour camps. Tamm spoke only Estonian at home and attended Estonian-language school on Saturdays. She did not begin learning English until she was enrolled in primary school. At age 11, she won a scholarship to attend Bradford Girls' Grammar School and joined the city's Civic Theatre. She was a graduate and an associate member of the Royal Academy of Dramatic Art, where she studied from 1969 to 1971.