Dillon, Eleanor Mary (c.1601–1629), nun, was born at Killenfaghny, Co. Westmeath, one among five daughters and seven sons of Theobald Dillon (qv) (d. 1624), 1st Viscount Dillon of Costello-Gallen, Co. Mayo, and his wife Eleanor, daughter of Sir Edward Tuite of Tuitestown, Co. Westmeath. Together with her sister Cecily Dillon (qv) (d. 1653), Eleanor Mary founded the Poor Clare movement in Ireland. She made her noviciate with the exiled English Poor Clares at Gravelines in Flanders, whose rule was one of the most austere in the church. The two Dillon sisters were professed on the feast of Our Lady's Nativity (8 September) 1622 as Sister Eleanor Mary of St Joseph and Sister Cecily of St Francis. In 1625, Sister Eleanor headed a party of five young Irish nuns who left Gravelines for Dunkirk to found the first convent for Irish women since the suppression of the monasteries. They stayed only a short time at Dunkirk as the living was expensive and it became difficult to pay the rent of their convent. In November 1626 they moved to Nieuport in Flanders, where they established a convent early in 1627.
It was at this time that two brothers of Eleanor and Cecily, Louis (formerly Edward) and George, both priests in the Irish province of Franciscans, suggested that the sisters come home to found a convent in Ireland. It was a period of some toleration. King James was negotiating the Spanish match for Prince Charles, and although this came to nothing, the prince married another catholic, Henrietta Maria, daughter of the king of France. In Ireland the more benign atmosphere encouraged catholics to practise openly and many of the religious orders established oratories. The sisters returned to Ireland around the feast of St Anthony (13 June) 1629, and established a Poor Clares convent at Merchants’ Quay in Dublin with Eleanor as the abbess. Their arrival about that date is noted in a provincial chapter of the Irish Franciscans held at Limerick on 15 August 1629, and a decree was formulated by which they were accepted as incorporated in the Irish province. The precise date of Eleanor's death is not known, but she died in 1629 as the new community was being established, and her sister Cecily took her place as abbess. Shortly afterwards a government campaign against the religious orders forced the convent to close and the Poor Clares moved from Dublin to make a fresh start on the Dillon estates at Ballinacliffey on the shore of Lough Ree, Co. Westmeath, in 1631.