William Penney, Baron Penney (1909–1991) was an English mathematician.
William Penney may also refer to: William Penney, Lord Kinloch (1801–1872), Scottish judge William F. Penney (1862–1934), Newfoundland judge and politician See also William Penny (1809–1892), Scottish whaling captain and explorer William Penny (rugby union), English rugby union player Will Penny, 1968 western film