Cosby Godolphin Trench DL, JP (6 January 1844 – 9 December 1925), styled The Honourable from 1855, was a British soldier and magistrate. He was the second son of Frederick Trench, 2nd Baron Ashtown and his first wife Harriet Georgiana Cosby, youngest daughter of Thomas Cosby. Trench was educated at Eton College and then at Corpus Christi College, Oxford. He entered the British Army as cornet in the 1st Dragoons in 1863, was promoted to captain in 1871 and retired five years later. In 1886, he was appointed High Sheriff of Tipperary. He was Justice of the Peace for County Waterford as well as County Tipperary and represented the latter also as Deputy Lieutenant.