O'Callaghan, May (1881–1973), journalist, translator and communist, was born Julia Mary O'Callaghan in Wexford town on the 14 August 1881, the youngest of four children born to Patrick O'Callaghan, RIC head constable, and Jane O'Callaghan (née Boland). Although initially resident in Wexford town, the middle-class and Roman catholic O'Callaghan family relocated to the coastal village of Ballinesker sometime after May's birth. In the late 1890s, O'Callaghan moved to Vienna, Austria, where she became involved in the city's literary circles and lectured at various locations on Irish literary topics; she also tutored in English while attending the University of Vienna.
In 1914, O'Callaghan moved to London and became involved with the East London Federation of Suffragettes (ELFS), an organisation led by Sylvia Pankhurst that campaigned for suffrage and the socialist transformation of society. Pankhurst memorialised O'Callaghan in her memoir of the first world war as the witty sub-editor of the ELFS journal the Woman's Dreadnought. During this period, O'Callaghan carried out administrative tasks in the paper's office on Fleet Street and the headquarters of Pankhurst's ELFS at 400 Old Ford Road. O'Callaghan also contributed a wide range of articles to the paper, including profiles of Irish nationalist figures such as Constance Markievicz (qv) and Laurence Ginnell (qv), in addition to a reportage piece on the Irish cooperative movement and notes on parliamentary happenings in Westminster.
In 1917, the Woman's Dreadnought was retitled the Workers' Dreadnought as Pankhurst's organisation, now retitled the Workers' Socialist Federation, took a sharp leftward turn. Pankhurst and her organisation ebulliently welcomed the October Revolution. Around 1919, Pankhurst appointed O'Callaghan manager of the People's Russian Information Bureau, an organisation partly funded by Soviet representatives in London and tasked with disseminating pro-Soviet propaganda from its Fleet Street headquarters. Pankhurst was ultimately expelled from the Communist Party of Great Britain which she had helped establish due to her anti-parliamentarianism. O'Callaghan appears to have broken with Pankhurst's politics as she followed her friends Rose and Nellie Cohen, two East London sisters who were also former members of the ELFS, into the nascent social world of orthodox British Communism.
Known to friends and comrades as 'O'C', in July 1924, O'Callaghan emigrated to Moscow to work in the headquarters of the Communist International (Comintern), the organising body of world Communist Parties. Her knowledge of English, German and Russian, the working languages of the Comintern, in addition to French, made her a versatile employee within the Comintern administrative apparatus. Her role as head of the English translation department of the press section of the Comintern is described in the memoir of Joseph Freeman, a leading figure of the American literary left, who worked under O'Callaghan during his 1926–7 stint in Moscow. During her time there, O'Callaghan was involved with the publication of Liam O'Flaherty's (qv) work into the Russian language and assisted visiting Western intellectuals by introducing them to their Soviet counterparts. O'Callaghan, writing under the pseudonym 'Eugene Fogarty', also penned what is considered by Joycean scholar Neil Cornwell to be the first critical essay on the work of James Joyce (qv) published in the Russian language. In 1928, she left Moscow to assist her friend Nellie Cohen through a pregnancy. She never returned to the Soviet Union.
In August 1928, O'Callaghan accompanied Nellie Cohen to New York, where Cohen gave birth to her daughter Joyce Isabelle Cohen in February 1929 (later known as Joyce Rathbone). O'Callaghan remained in New York until 1933 working for various Soviet cultural outfits before returning to London.
During the last decades of her career, O'Callaghan worked in a left-wing London bookstore. She never had children or married. She infrequently returned to Ireland but remained in contact with an elder sister. She died at the age of ninety-one in a North London nursing home on 18 May 1973. A small portion of her private archive survived, consisting of correspondence between O'Callaghan and O'Flaherty that was published in A. A. Kelly (ed.), The letters of Liam O'Flaherty (1996).