Sir William Meredith, 3rd Baronet (c.1725 – 2 January 1790) was a British politician of the late 18th Century, one of the Rockingham Whigs.
He was the son of Amos Meredith (1688-1745) of Chester and Anne St. John, his second wife and was educated at Christ Church, Oxford. He was one of nine children; 1. Anna-Maria, 2. Mary, 3. Elizabeth, 4. Henrietta (married Hon. Frederick Vane, brother of Henry Vane, 2nd Earl of Darlington), 5. William (himself), 6. Martha, 7. Theophilus, 8. Anna-Margaretta (third wife of Assheton Curzon, 1st Viscount Curzon), and 9. Mary (widow of the infamous Laurence Shirley, 4th Earl Ferrers, later married Lord Frederick Campbell). In 1752 he inherited his title and estates on the death of his grandfather, Sir William Meredith, 2nd Baronet.
Meredith represented Wigan in the House of Commons from 1754 to 1761, and then Liverpool until 1780. From 1765 to 1766, he briefly served as a Lord of the Admiralty. He was sworn of the Privy Council and appointed Comptroller of the Household in 1774.
He was an extravagant man and in 1779 was obliged to sell the family estate at Henbury, Cheshire to John Bower Jodrell for £24,000.
He died in Lyons, France on 2 January 1790. He had never married and the baronetcy became extinct. The town of Meredith, New Hampshire is named for him.