Margaret Sheila Mackellar Chisholm (9 September 1895 – 13 October 1969) was an Australian socialite and "it girl" in British high society during and after World War I.

She married three times: Francis St Clair-Erskine, Lord Loughborough (heir to the Earldom of Rosslyn); Sir John Charles Peniston Milbanke, 11th Bt; and Prince Dmitri Alexandrovich of Russia.

Chisholm's romantic liaison with Albert ended when his father, George V, told him to leave "the already-married Australian" and find someone more suitable.

[4] The Chisholms became wealthy members of the Squattocracy in New South Wales, and she was raised on "Wollogorang" with her two older brothers, John and Roy.

[9] They planned to spend months in Europe, but their trip was extended by the onset of the First World War, making the long journey back to Australia too dangerous.

Their younger son, Peter, a Royal Air Force pilot, was killed on active service in September 1939 in the first weeks of the Second World War.

[9] Chisholm had fallen into obscurity by the time of her death and was almost completely forgotten until the publication of journalist Robert Wainwright's 2014 biography Sheila: The Australian Beauty Who Bewitched British Society.