Lieutenant Colonel Sir John Robert Chancellor GCMG, GCVO, GBE, DSO (1870–1952) was a British soldier and colonial official.
After a career in the British Army's Corps of Royal Engineers, which included service on the North West Frontier and being Secretary of the Colonial Defence Committee, he became a colonial administrator serving as the 20th Governor of Mauritius from 13 September 1911 to 28 January 1916,Trinidad and Tobago (1916–1921) and Southern Rhodesia (1923–1928). He also served as Principal Assistant Secretary to the Committee of Imperial Defence From 1922–1923.
In 1898 he was awarded the Distinguished Service Order (DSO). In 1909 he was appointed a Companion of the Order of St Michael and St George. He was knighted in the 1913 King's Birthday Honours when he was made a Knight Commander of the Order of St Michael and St George (KCMG). In the 1922 Dissolution Honours List he was promoted to Knight Grand Cross of the Order of St Michael and St George (GCMG). He was appointed a Knight of Justice in the Venerable Order of Saint John on 19 December 1928.