Francis Arthur Macarthur-Onslow (7 June 1879 – 3 March 1938) was an Australian grazier and real estate investor.
After service in the South African War, he raised sheep, was a director of the Camden Park Estate and its associated dairy farm, and finally moved to Camden to invest in real estate and travel extensively.
He was promoted lieutenant in July 1899, and served in the South African War from 1900 to 1901 with the 7th Dragoon Guards.
Macarthur-Onslow saw fighting at Johannesburg, Diamond Hill, and Bergendal before contracting rheumatic fever, from which he recovered in London.
On 16 May 1903, he married Sylvia Seton Raymond Chisholm, by whom he had four children: He went into the reserve of officers in 1907 and retired as a lieutenant in 1919.