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.

Many of the 48th were coal miners, and Pleasants supposedly heard his men suggest running a shaft under the Confederate lines.

However, the Union troops, under Ambrose Burnside, failed to take advantage of the explosion and suffered considerable casualties in what is known as the Battle of the Crater.

[1] Harry Turtledove's alternate history novel The Guns of the South features Pleasants as a significant character.