Ormsby MacKnight (or McKnight) Mitchel (August 28, 1810, or possibly 1809, – October 31, 1862) was an American astronomer and major general in the American Civil War. A multi-talented man, he was also an attorney, surveyor, professor, and publisher. He is notable for publishing the first magazine in the United States devoted to astronomy. Known in the Union Army as "Old Stars", he is best known for ordering the raid that became famous as the Great Locomotive Chase during the American Civil War.