Falkiner, Caesar Litton (1863–1908), lawyer and historian, was born in Dublin on 26 September 1863, the second son in the family of three sons and four daughters of Sir Frederick Richard Falkiner (qv) and his first wife, Adelaide, daughter of Thomas Sadleir of Castletown, Borrisokane, Co. Tipperary, who was high sheriff of that county in 1859. His forename Cæsar came from a friend of the family, Cæsar Otway (qv); Litton was his paternal grandmother's maiden name. He was educated at the Royal School, Armagh, before entering TCD where he was president of the Philosophical Society in 1885–6, and where he graduated BA in 1886 and MA in 1890.
He was called to the Irish bar in 1887, and then practised, also involving himself in local unionist politics and contributing leading articles to the Dublin Daily Express. At the parliamentary elections of 1892 he stood unsuccessfully as a candidate in South Armagh; at the elections of 1895 he organised countrywide the campaign of the Irish Unionist Alliance. A believer in state intervention, Falkiner advocated an extension of the powers and resources of the Congested Districts Board, the creation of a department of agriculture and the provision of technical education as well as full recognition of and financial aid for a catholic university, all of which he saw as benefits justifying Ireland's continuing union with Great Britain. In 1898 he was appointed an assistant land commissioner, a position requiring much travel in the west and south of Ireland and leading to his appointment to the staff of the Land Commission in 1905.
He found time for the study of Irish history and literature and was elected MRIA (1896), serving as secretary of council during the last eighteen months of his life. Between about 1890 and his death Falkiner read seven papers to the academy and contributed many more, some on contemporary political and social issues but most on historical subjects, to the Edinburgh Review and other journals. He contributed twenty-nine articles to the Dictionary of national biography and edited for the Historical Manuscripts Commission the Calendar of the manuscripts of the marquess of Ormonde (volumes i–v, 1902–8). Though he never produced a historical monograph, some of his published papers were collected as Studies in Irish history and biography mainly in the eighteenth century (1902), Illustrations of Irish history and topography mainly of the seventeenth century (1904) and Essays relating to Ireland, biographical, historical and topographical (1909). At the time of his death (at the age of forty-five) he was beginning an attempt to rescue the reputation of the poet Thomas Moore (qv), by preparing a new edition of his poetical works, having already published a selection in 1903.
Arguably Falkiner was the most brilliant Irish historian at the turn of the century: his interests were astonishingly varied – in several cases (for example, the Phoenix Park and the Ouzel Galley Society) highly unusual – and were pursued with tremendous zeal, energy and imagination. He paid close attention to primary sources, manuscripts as well as printed books, believing that the historian should assemble and assess all the evidence available before forming a judgement; yet despite this thoroughness his productivity was phenomenal and because of it his productions have stood the test of time. He wrote with lucidity and in a sympathetic tone.
His death occurred in France on 5 August 1908 as a result of a fall when walking in the Alps near Argentière (Hautes-Alpes). He was buried at Chamonix (Haute-Savoie) and a plaque to his memory was erected in St Patrick's cathedral, Dublin. He married on 4 August 1892 Henrietta Mary, daughter of Sir Thomas Newenham Deane (qv), and with her had two daughters, the younger of whom, Irene Kathleen (b. 17 March 1897), survived him by almost ninety years, dying unmarried on 1 May 1998. The family lived at Mount Mapas, Killiney, Co. Dublin.