Major General James William Macarthur-Onslow, VD (7 November 1867 – 17 November 1946) was a soldier, grazier and politician. The son of a prominent New South Wales family, he was commissioned in the New South Wales Mounted Rifles in 1892 and served in the Chitral Expedition, Second Boer War and the First World War. Afterwards, he served in the New South Wales Legislative Assembly and New South Wales Legislative Council.