Sheila Sim (5 June 1922 – 19 January 2016) was an English actress, and the wife of actor Richard Attenborough and the older sister of actor Gerald Sim. They appeared on stage together in the Agatha Christie play The Mousetrap in its original cast in 1952. She played the role of Mollie Ralston.
She appeared as Tuppence Beresford in the 1953 radio series Partners in Crime. Her husband played Tommy Beresford.
In the 2022 film See How They Run, a fictionalised version of her is portrayed by actress Pearl Chanda.