William Moseley Swain (May 12, 1809, Manlius, New York – February 16, 1868, Philadelphia, Pennsylvania) was an American journalist and businessman.
He was one of the founders and proprietors of the Philadelphia Public Ledger and also served as editor. The paper was the first daily to establish a pony express, and one of the first to use the telegraph. In 1847, it was printed on the first rotary press ever built.
In May 1845, he was one of the incorporators of the pioneering Magnetic Telegraph Company, and from 1850 its president. In this company, he was an associate of the inventor, Samuel F. B. Morse, and the chief promoter, Amos Kendall, another former newspaperman.
Swain was buried in The Woodlands Cemetery.