William Littlejohn O'Halloran (5 May 1806 – 15 July 1885) was a British Army officer and public servant in South Australia.
[3] He entered the army as ensign in the 14th Foot in 1823 (or 11 January 1824),[2] and after brilliant service in India, particularly at the siege and storming of Bhurtpore, Bengal (medal), obtaining his lieutenancy in action.
[2] In April 1827 he exchanged into the 38th regiment;[2] served on the staff, with his brother, Major T. S. O'Halloran,[3] of his father at Saugor, Central India; and was employed on recruiting service in Belfast from 1832 to 1834.
[2] O'Halloran emigrated to the colony of South Australia, arriving in Port Adelaide in August 1840 aboard the barque Lalla Rookh.
He was appointed Auditor-General, in succession to Francis Singleton, in 1851, and held the position till 1868, when he finally retired from the public service.