Robert Darcy, 4th Earl of Holderness PC (17 May 1718 – 16 May 1778), known before 1721 as Lord Darcy and Conyers, was a British diplomatist and politician. From 1744 to 1746 he was ambassador at Venice and from 1749 to 1751 he represented his country at The Hague. In 1751 he became Secretary of State for the Southern Department, transferring in 1754 to the Northern Department, and he remained in office until March 1761, when he was dismissed by King George III in favor of Lord Bute, although he had largely been a cipher in that position to the stronger personalities of his colleagues, successively the Duke of Newcastle, Thomas Robinson, Henry Fox, and William Pitt the Elder. From 1771 to 1776 he acted as governor to two of the King's sons, a solemn phantom as Horace Walpole calls him. He left no sons, and all his titles became extinct except the Baronies of Darcy (de Knayth) and Conyers, which were Baronies by Writ. In those peerages he was succeeded by his daughter, Amelia Osborne, Marchioness of Carmarthen.