Lowther, Sir Gerard (Gerrard, Gerald, Garret) (d. 1624), justice of the common pleas in Ireland, was the son of Sir Richard Lowther (1529–1607), lord warden of the western marches, and his wife Frances, daughter of John Middleton of Middleton, Westmorland, England. He attended the Inner Temple, perhaps entering in 1580; was fined in November 1589 for wearing his hat in church, possibly indicating puritanical tendencies; and was called to the bar (1590). He apparently practised in England for the next twenty years, until he was appointed a justice of the common bench in Ireland on 12 October 1610. Fourth in seniority in the common bench in 1611, he received £266 13s. 4d. that year. An active justice of the court until his death, he dealt with cases such as the examination of rebels (1615) connected with a plot by Alexander MacDonnell and Rory Óg O'Cahan to burn Coleraine, Lifford, and other places in Ulster, and the following year he was one of the judges who investigated the royalties of the liberty of Tipperary and found that the earl of Ormond had no legitimate claim to palatinate status there. As was the practice, he was admitted to the King's Inns on 7 November 1610, and six years later he was its treasurer. Subsequently he became one of its trustees. For his services he received a knighthood (3 May 1618).
Aside from his legal career, he had extensive estates in Co. Tyrone and Co. Fermanagh, having at least 1,000 acres in each county by 1618. He built a house near Lowtherstown, Co. Fermanagh, received a patent on 20 February 1618/19 to hold a fair there, and appointed his brother Hugh to look after his interests in Ulster. Lowther married first (date unknown) Grace, daughter of Alan Bellingham of Levens, Westmorland; and secondly (date unknown) Anne, daughter and co-heir of Sir Ralph Bulmer of Wilton, Durham. Neither marriage produced children. He made his will on 24 September 1624, in which he dispersed his estate among his brothers William, Hugh, and Lancelot, his nephew Richard, and his godson, Gerald Lowther (qv), who subsequently became chief justice of the common bench in Ireland. He died 14 October 1624, and was buried five days later in Christ Church cathedral, Dublin.