Simon Cameron, American journalist and politician, 26th United States Secretary of War (d. 1889)
Simon Cameron (March 8, 1799 – June 26, 1889) was an American businessman and politician. He represented Pennsylvania in the United States Senate and served as United States Secretary of War under President Abraham Lincoln at the start of the American Civil War.

A native of Maytown, Pennsylvania, Cameron made a fortune in railways, canals, and banking. He was elected to the United States Senate as a member of the Democratic Party in 1845. A persistent opponent of slavery, Cameron briefly joined the Know Nothing Party before switching to the Republican Party in 1856. He won election to another term in the Senate in 1857 and provided pivotal support to Abraham Lincoln at the 1860 Republican National Convention.

Lincoln appointed Cameron as his first Secretary of War. Cameron's wartime tenure was marked by allegations of corruption and lax management, and he was demoted to Ambassador to Russia in January 1862. Cameron made a political comeback after the Civil War, winning a third election to the Senate in 1867 and building the powerful Cameron machine that would dominate Pennsylvania politics for the next seventy years.