O'Shiel, Kevin Roantree (1891–1970), barrister and land commissioner, was born 23 September 1891 in Omagh, Co. Tyrone, eldest of four sons and two daughters of Francis Shields , solicitor, and his wife Elizabeth, daughter of D. J. Roantree, school inspector. While his father retained the name ‘Shields’, his mother and the rest of the family used the form ‘O'Shiel’. His great-uncle was James Shields (qv), US soldier and politician. Educated at Mount St Columba's CBS, Omagh, convent preparatory schools in Oxford and Bath, St George's School, Surrey, and Mount St Mary's Jesuit school, Derby, O'Shiel studied law at TCD and the King's Inns, and having been called to the bar (Michaelmas term 1913) joined the north-west circuit.
A member of the Irish Volunteers until the split in 1914, he was initially a home rule nationalist, but became disillusioned by the postponement of home rule in 1914, and with the policies of the Irish party. Increasingly influenced by separatism, in 1916 (after the Irish party had accepted the exclusion of Ulster from home rule) he joined the Anti-Partition League (later the Irish National League), formed by Ulster nationalists opposed to the Irish party. Having campaigned for Sinn Féin candidates during the 1917 by-elections in Roscommon, Longford, and Clare, he joined that party in 1917 after the dissolution of the Irish Nation League and became a member of the Owen Roe branch in Omagh, which he represented at the Sinn Féin convention in October 1917. Prominent in the anti-conscription campaign in mid Tyrone in 1918, and supervisor of the Ballyjamesduff district for Sinn Féin in the Cavan East by-election (June 1918), he was an unsuccessful Sinn Féin candidate in the 1918 general election in the constituencies of Fermanagh North and Antrim South. Recruited as land commissioner by Arthur Griffith (qv) in May 1920 to deal with the resurgence of land agitation in the west, from September 1920 he was judicial commissioner of the newly established dáil land commission. Noted for the sagacity of his judgments, together with Conor Maguire (qv) he was largely responsible for the success of the dáil land courts, although their effectiveness was curtailed during 1921 by British efforts to suppress the republican courts. In 1921 he wrote a series of articles arguing that a boycott of British goods would be of economic benefit to Ireland.
A supporter of the Anglo–Irish treaty, in 1922 he was assistant legal adviser to the provisional government, during which he was involved in drawing up plans for the pact election, conducted an inquiry into a May 1922 mutiny by garda recruits, and supported action by the government to secure the release of republican internees on the Argenta prison ship in Belfast, among whom was his friend Cahir Healy (qv). He served in 1922 as adviser to Michael Collins (qv) on Northern Ireland affairs, and in 1922/3 was assistant legal adviser to the provisional government and the Irish Free State. In January 1923 he wrote a memo urging the government to hasten the end of the civil war, and from October 1922 to November 1925 was director of the Free State government's North-Eastern Boundary Bureau, which was established in October 1922 to compile data for the boundary commission. As part of this work he was sent to Geneva to examine material from other boundary commissions at the League of Nations archives. From 1923 he served as commissioner with the Irish Land Commission until his retirement in 1963. The author of a number of articles on the history of partition and Irish land settlement, his principal publications include The rise of the Irish Nation League (1916), The making of a republic (1920), a history of the American revolution, and (with T. O'Brien) The land problem in Ireland and its settlement (1954). His hobbies included reading, ornithology, botany, and walking. He lived at 28 Kenilworth Road, Dublin, and died 12 July 1970 in Dublin, leaving an estate valued at £738.
He married (6 September 1922) Louise F. Conry, daughter of John Conry, medical doctor, of Dublin; they had two sons who did not survive infancy, and after her death he married (15 October 1929) Cecil, daughter of T. A. Smiddy (qv), economist and diplomat, of Cork, and his wife Lilian, daughter of Cornelius O'Connell, of Cork. They had two daughters. O'Shiel's papers, including an unpublished memoir of the revolutionary period, were left in the possession of his daughter Eda Sagarra, MRIA, professor of German at TCD.