John Joseph “J.J.” “Sceilg” O’Kelly (Seán Ua Ceallaigh) was born on Valentia Island, Co. Kerry, 7 July 1874 to Patrick and Ellen Kelly (née O'Sullivan). Though he would spend the vast majority of his adult life in Dublin, leaving Valentia in 1897, O’Kelly’s identification with his Kerry heritage would remain a defining characteristic.

O’Kelly learned Irish from his father and from various storytellers on Valentia, eventually becoming a notable teacher of the language as well as an Irish language activist. In 1901 O’Kelly founded the Keating Branch of the Gaelic League with Shan Ó Cuív, Tadhg “Torna” Ó Donnchadha, and Risteard Ó Foghludha. The Keating Branch had an often acrimonious relationship with the executive of the Gaelic League, including two incidents involving O’Kelly: in 1903 P.H. Pearse was selected as the editor of An Claidheamh Soluis over O’Kelly and in 1905 Douglas Hyde and other executive members intervened with the Freeman’s Journal to remove O’Kelly from his position.

Sceilg was additionally a prolific writer and journalist, writing the daily Irish column for the Freeman’s Journal (1901-1905). From 1901-1906 he was the editor of Banba, the magazine of the Keating Branch of the Gaelic League. In 1911 he was named to the editorship of M.H. Gill’s new journal, The Catholic Bulletin: a Monthly Review of Catholic Literature.

In the months and years following the Rising, The Catholic Bulletin proved to be a major source of information on the Rising rebels, coming out in support of their cause, despite the threat of censorship under the terms of the Defense of the Realm Act 1914. The circulation of the The Catholic Bulletin was significant and may have played a role in shaping public opinion on the Rising. O’Kelly held the position of editor until 1922 when he left Ireland for America to advocate for the Republic.

Following the Rising, O’Kelly, alongside Fr Michael O’Flanagan campaigned on behalf of Count George Noble Plunkett, father of Rising leader Joseph Plunkett, for the Roscommon North by-election. In February 1917 O’Kelly, along with thirty others, was deported as part of the so-called “German Plot.” Months after his June 1917 release, O’Kelly played a role in planning Sinn Féin’s October 1917 convention. In the 1918 General Election Sceilg was elected as MP for Louth; he followed Sinn Féin’s abstentionist policy with Westminster and took his seat in the First Dáil on 21 January 1919.

Due to Sean T. O’Kelly’s prolonged absence from Dáil Eireann, Sceilg was effectively Ceann Chomhairle of the First Dáil from April 1919 until his resignation as Leas-Cheann Chomhairle on 26 August 1921. He was also appointed as Minister for Irish in November 1919, serving until August 1921 when he was appointed Minister for Education. Due to his involvement in Dáil Eireann, his Gaelic League presidency (from 1919), and his role as editor at The Catholic Bulletin, O’Kelly was eventually arrested on 8 March 1921 and jailed at Arbour Hill Prison until May 1921.

O’Kelly opposed the initial gestures towards a truce in the summer of 1921 and opposed the final Anglo-Irish Treaty. From March - May 1922 he undertook a republican mission to America as a representative of Cumann na Poblachta alongside Austin Stack and Countess Markievicz, often working in tandem with the American Association for the Recognition of the Irish Republic (A.A.R.I.R.). In September 1922 De Valera would send Sceilg back to the US along with Joseph O’Doherty to finish his previous work. O’Kelly and Fr. O’Flanagan left for Australia for a similar mission in March 1923 after De Valera had named Laurence Ginnell as the envoy to America. While O’Kelly and O’Flanagan were welcomed by Archbishop Daniel Mannix, they found themselves in opposition to the authorities and were arrested twice. After a six week stint in prison in Sydney they were deported to the United States in July 1923. Following Ginnell’s death in September 1923 O’Kelly was named as envoy to America, a position he held until 1924.

On his return to Ireland in November 1924, O’Kelly was elected Ceann Chomhairle of the rump Second Dáil. By 1925, however, De Valera began to waiver in his commitment to opposition to the Oath of Allegiance, attempting to reconcile Sinn Féin with the Free State; O'Kelly maintained a hardline stance. De Valera and O’Kelly would continue to clash on this issue, an example of the schism growing amongst the former anti-treaty factions. In March 1926 De Valera would resign as President of Sinn Féin, forming Fianna Fáil in opposition in April 1926. O’Kelly was elected President of Sinn Fein in October of that year, remaining a major opponent of De Valera and Fianna Fáil for the next decade along with maintaining the republican legitimatist position in relation to the continuity of the Second Dáil. In 1938, O’Kelly and the remaining seven hold-outs of the Second Dáil delegated their authority to the Irish Republican Army via IRA Chief of Staff Seán Russell.

Particularly given the vein of antisemitism running through his writings, including within his pamphlet “Stepping Stones” (1939), it is unsurprising that O’Kelly expressed open admiration for Adolph Hitler’s Nazi regime, visiting Germany in 1938. Various Sinn Fein publications from the 1930s also bore the marks of Sceilg’s antisemitism, attacking Jewish influence in Ireland. O’Kelly’s antisemitism in this period went hand in hand with an admiration for fascism more generally: O’Kelly, alongside the Catholic church and a number of other republicans, supported Franco during the Spanish Civil War, going so far as to oppose those members of the IRA who chose to go to Spain and fight Franco.

While he increasingly withdrew from public political life as he aged, O’Kelly continued to write numerous articles, pamphlets, essays and eulogies, including those for his close friends, Fr Michael O’Flanagan and (1876-1942) George Noble Plunkett (1851-1948). Sceilg died 26 March 1957 and was buried in Glasnevin Cemetery.

O’Kelly wrote under a variety of pseudonyms beyond ‘Sceilg’ including: Mogh Ruith, An Dairbhreach Dána, An Fear Siubhail, and Sceilg na Sceol.

J.J. O’Kelly married Nora O’Sullivan (1875 - 1949), daughter of Patrick O’Sullivan of Lisbawn, Co. Kerry in 1904. They had six children, five of whom lived to adulthood: Pádraig O’Kelly (1906-1928), Seán Óg O'Kelly (1908-1975), Donnchadh O’Kelly (1909-1911), Máire O’Kelly (1910-1937), Mortimer O’Kelly (1912-1989), and Catherine “Iney” O’Kelly (b. 1914).

Seán Óg O’Kelly was born in Dublin in 1909 to J.J. O'Kelly and Nora O'Kelly (née O'Sullivan). married née O'Sullivan; they had five children. Seán Óg served as secretary of the Gaelic League in the 1930s and later as a Rights Commissioner for Irish labor disputes.