Arthur Onslow Whitington (1858 – 14 May 1919), generally known as A. O. Whitington or simply "A.O.", was a businessman and sportsman in South Australia, the highly regarded founding secretary of the revived South Australian Jockey Club, serving from 1888 to 1919. The writer proved correct: largely due to Whitington's scrupulous management, the SAJC was able in 1895 to exercise its "right to purchase" from Browne, who had in the interim acquired Pell's then Wigley's shares. His successor at Morphettville was Arthur V. Kewney, previously secretary to the .