Colonel Sir William Owen Lanyon KCMG CB (21 July 1842 – 6 April 1887) was a British colonial administrator and British Army officer.
Lanyon was born in County Antrim, Ireland, to Sir Charles Lanyon and his wife Elizabeth Helen Owen. He was educated at Bromsgrove School before joining the ; he was commissioned into the 6th Foot in 1860, but transferred to the 2nd West India Regiment in 1866. He became private secretary to Sir John Peter Grant, Governor of Jamaica from 1868 to 1873.
In South Africa, he took over administration of Transvaal from Sir Theophilus Shepstone on 4 March 1879, and remained in that position until 8 August 1881. He then served in the 1882 Anglo-Egyptian War.
Lanyon became a Companion of the Order of the Bath in 1878 and a Knight Commander of the Order of St Michael and St George in 1880. He died of cancer in 1887 in New York.