Henry Clay Pleasants (February 16, 1833 – March 26, 1880) was a coal mining engineer and an officer in the Union Army during the American Civil War. He is best known for organizing the building of a tunnel filled with explosives under the Confederate lines outside Petersburg, Virginia, which resulted in the Battle of the Crater on July 30, 1864. The Union troops, however, failed in their opportunity to break the Siege of Petersburg.