MacDonnell, Randell (c.1633–1711), naval commander and Jacobite, was second son of Sir James MacDonnell, 2nd baronet of Moye, a cousin of Randal MacDonnell (qv), 2nd earl and later marquis of Antrim. His mother was Mary MacDonnell, a daughter of Sir Donough O'Brien. MacDonnell's early life remains obscure. He may have served in the English army, but eventually he joined the navy, which was not yet barred to catholics. He served in the Mediterranean as a ‘volunteer’ in 1674, subsequently rising through the ranks. In March 1678 he was third lieutenant of the Charles, but his catholicism proved to be a hindrance; his eventual promotion to captain was delayed until August 1681. He subsequently received command of the Golden Horse. After transporting the first Moroccan ambassador to England in December 1681, he joined the entourage of James (qv), duke of York, as a gentleman usher, becoming acquainted with Col. Richard Talbot (qv), later earl of Tyrconnell. In 1682 MacDonnell saved the duke of York when his ship, the Gloucester, ran aground en route to Edinburgh; he held off the irate crew at swordpoint, and York afterwards promoted him to equerry. In autumn 1683 he returned to the Mediterranean in command of the frigate Greyhound. In 1684 he was dismissed from York's household for criticising George Legge, earl of Dartmouth. MacDonnell's controversial naval career was spent mainly in the Mediterranean, where he distinguished himself in a number of engagements, eventually commanding a squadron and amassing considerable wealth. Returning to England at the end of 1686, he invested in Irish property; the birth of an heir to Alexander MacDonnell (qv), 3rd earl of Antrim, excluded him from a prospective inheritance.
MacDonnell benefited from the accession of York as James II. In August 1687 he successfully petitioned for the return of approximately 900 acres (364 ha) forfeited during the interregnum. He was also promoted, becoming captain of seniority on the Assurance (May 1688). However, the ship was damaged later in the year while shadowing the invasion fleet of William of Orange (qv), and MacDonnell was recruited to assist in James's escape to France. He engineered the escape of Queen Mary and her entourage on 10 December 1688. On 13 December, with the imminent dismissal of catholics from the navy, he resigned his command, and on 22 December, during a storm, he escorted James and his illegitimate son James Fitzjames (qv), duke of Berwick, to France in a fishing boat. He prudently took £150,000 for his own use, later investing it in France.
In exile, MacDonnell was made a gentleman of the bedchamber; he held the post until his death. In March 1689 he accompanied Patrick Sarsfield (qv) to Ireland, and subsequently sat in the Jacobite parliament as MP for Co. Antrim. He lost his Antrim estates after the Williamite campaign in the north, but secured property in Dublin and resided there. He was ordered back to France prior to the battle of the Boyne. In 1690 MacDonnell was involved in the dispute between Sarsfield and Tyrconnell over the issue of a negotiated end to the war; Tyrconnell identified MacDonnell as his foremost enemy at the Jacobite court. MacDonnell was indeed a persuasive advocate for Sarsfield, at one point arranging an audience on his behalf at Saint-Germain. After the war MacDonnell was attainted, and his estates were forfeited. In May 1692 he had a key role in plans for a Jacobite invasion of England. He persuaded James to send supplies to Ireland, and he himself sent emissaries to Ireland in anticipation of the invasion, being deeply involved in plans for a rising in Connacht. However, the invasion fleet was intercepted, and the project was abandoned. Unlike most Irish émigrés at the Jacobite court at Saint-Germain, MacDonnell enjoyed a comfortable existence, thanks to James's patronage and his own financial investments. In 1700–02 he was involved in a plan by Berwick for an invasion of Ireland. At one point he landed briefly in Kerry and met local Jacobites, but nothing came of this venture. He died at Saint-Germain in 1711.
MacDonnell married (1687) Hannah Roche (d. 1728), a former lady in waiting to Louise de Querouailles, mistress of Charles II; Sarsfield, an old friend, had acted as a witness. They had at least four sons and four daughters. MacDonnell vested some of his Irish estates in his wife's name to secure them from confiscation, and she returned to Ireland from Saint-Germain on this account (1695), taking all but three of the children. MacDonnell had another, illegitimate, daughter at Saint-Germain, Catherine. His three sons, James, René, and John-Richard, each succeeded to the baronetcy; the latter two were active Jacobites.