William Cogswell (1838–1895) was a U.S. representative from Massachusetts and a colonel in the Union Army during the American Civil War.
William Cogswell may also refer to: William Cogswell (New Hampshire physician) (1760–1831), surgeon's mate in the American Revolutionary War, physician, grandfather of the American politician and colonel William Cogswell William F. Cogswell (1819–1903), American portrait painter William Henry Cogswell (1798–1876), American physician and state senator William S. Cogswell Jr. (born 1975), member of the South Carolina House of Representatives