Thomas Swann (February 3, 1809 – July 24, 1883) was an American lawyer and politician who also was President of the Baltimore and Ohio Railroad as it completed track to Wheeling and gained access to the Ohio River Valley. Initially a Know-Nothing, and later a Democrat, Swann served as the 19th Mayor of Baltimore (1856–1860), later as the 33rd Governor of Maryland (1866–1869), and subsequently as U.S. Representative ("Congressman") from Maryland's 3rd congressional district and then 4th congressional district (1869–1879), representing the Baltimore area.