O'Bryen, Dennis (c.1755–1832), surgeon, dramatist, and political writer, was born in Ireland; no details of his parents are known. He abandoned a surgical career to become a writer, and by 1782 had settled in London, where he quickly established himself as a political satirist. A close friend of Charles James Fox, O'Bryen was aligned with the whigs throughout his writing career. In the early 1780s he published two papers entitled The reasoner which appeared (misattributed to Lord Erskine and Richard Brinsley Sheridan (qv)) in several compilations, but he first gained significant attention with the ironical pamphlet Defence of the earl of Shelburne from the reproaches of his numerous enemies (1782). It ran to a second edition in 1783 and provoked replies from Shelburne (qv). O'Bryen also ventured into dramatic writing; his comedy ‘A friend in need is a friend indeed’ was produced at the Haymarket (5 July 1783), but seems to have been unsuccessful and was never printed. His political writing continued to be trenchant and effective, usually targeting the administration of William Pitt. His publications include A gleam of comfort to this distracted empire, demonstrating the fairness and reasonableness of national confidence in the present ministry (1784); A view of the commercial treaty with France (1786); Lines written at Twickenham (1788); and Utrum horum? The government or the country (1796; ran to three editions).
He ably supported the whigs in the regency crisis of 1788 with the anonymously published pamphlet The prospect before us: being a series of papers upon the great question which now agitates the public mind (later reprinted with a new introduction in 1810, when George III became incapacitated). He was well acquainted with other Irishmen in London: in 1790 he helped reconcile Sheridan and Edmund Burke (qv), and in May 1798 attended the trial of Arthur O'Connor (qv) to demonstrate his support for the United Irishman. When O'Connor was acquitted, O'Bryen and Sheridan instigated a courtroom disturbance probably to assist O'Connor's escape from magistrates waiting to rearrest him. Consequently, O'Bryen was tried in April 1799 on charges of inciting riot; though he was acquitted, his co-accused, Robert Fergusson and Lord Thanet, were both found guilty and imprisoned.
On the change of ministry in 1806, O'Bryen was appointed deputy paymaster-general and later marshal of the admiralty patent office of the Cape of Good Hope; the latter position was reputedly worth some £4,000 a year. He maintained his Irish connections: he was a member of the Benevolent Society of St Patrick (which raised funds for the education of Irish children living in London), and secured subscriptions from the duke of Wellington (qv), George Canning, and Lord Castlereagh (qv), among others. In 1816 he wrote a letter to the Morning Post pleading for assistance for Sheridan (who was then in his last illness and troubled by financial concerns) and secured him a £400 loan. O'Bryen died 13 August 1832 at Margate, Kent, having resided at 21 Craven St., London. Some of his political correspondence (including letters to Fox and Sheridan) is in the BL.