McDonnel, Sir Edward (1806–60), merchant and paper manufacturer, was born in Dublin, son of Christopher McDonnel, also a merchant and paper manufacturer, and his wife Ann, daughter of Edward Brennan, all from Dublin. Although one of the most eminent and successful merchants in the city, McDonnel's father was a catholic and was frustrated by restrictions imposed by the remaining penal laws; consequently, he supported Daniel O'Connell (qv) and took an active part in the struggle for emancipation. From 1750 until the mid-Victorian period the name McDonnel (or ‘McDonnell’) was the most important one in Irish papermaking: various branches of the family had paper mills in Tallaght, Saggart, and Templeogue. Christopher McDonnel owned Killeen mills near Ballyfermot, an impressive establishment resembling a small town, which provided homes for most of its 150 workers and their families; from 1802 its head office was located at 9 Merchant's Quay. In 1830 Edward (and presumably a brother) joined the firm, which was renamed Christopher McDonnel & Sons.
On his father's death (c.1830s) Edward became head of the company, and by 1858 had acquired additional mills in Clondalkin and Newhaggard. He was apparently well liked by his employees, and was known for fairness, conciliating demeanour, and kindly face. He served as chairman of the Great Southern & Western Railway Company (May 1849–1860), utilising his customary zeal, good sense, and efficiency to oversee its expansion. His tact and good temper ensured that he could deal with conflicting interests, difficult questions, and heated debates. In 1849 he was knighted by the lord lieutenant, the earl of Clarendon (qv), on the opening of the trunk line from Dublin to Kilbarry, Co. Cork.
McDonnel did not restrict his talents to enterprise, but instead chose to expand his interest into the area of local government. When the Irish corporate reform act (1840) was passed, it revolutionised municipal government by allowing catholics to sit on city councils for the first time since 1689. He served as a Dublin city councillor for many years (1843–5, 1853–60), and sided with the corporation's liberal–catholic majority in supporting the promotion of catholic rights, the implementation of sanitary reform, and the expansion of the council's powers. Admired and respected by people of all ranks and religions, he was elected lord mayor in 1854. His most memorable act as mayor was perhaps the grand ball given in honour of Ireland's first regiment bound for the Crimea (February 1854); it was a celebration said to have been reminiscent of the one held years before by the duke of Richmond (qv) in honour of Irish troops departing for Waterloo. McDonnel was also munificent in his charitable contributions, and is said to have donated large amounts without ever seeking acclaim or praise. After suffering for many years from heart disease, he died 22 November 1860 at his home at 31 Merrion Square South. His funeral was attended by the nobility, gentry, and professional men of Ireland and by hundreds of his workers; he was buried near O'Connell in Glasnevin cemetery.
McDonnel was married for many years. Details of his marriage are lacking, but he was the father of three sons and three daughters; his eldest son, Capt. Christopher McDonnel, served with great distinction throughout the Crimean war (1854–6).