William Fawcett (26 December 1763 – 28 December 1844) was an engineer and manufacturer of guns and steam engines, supplying steam engines for some of the earliest steam ships in Britain and America, and for use on sugar plantations in America. He was a partner in the firm of Fawcett, Preston and Company, which supplied the steam engines for a number of ships, including the paddle steamer William Fawcett, described as the first ship operated by what would become the Peninsular and Oriental Steam Navigation Company (P&O).