Marcus Daly was an Irish-born American businessman known as one of the four "Copper Kings" of Butte, Montana, United States.

The Copper Kings were industrialists Marcus Daly, William A. Clark, James Andrew Murray and F. Augustus Heinze. They were known for the epic battles fought in Butte, Montana, and the surrounding region, during the Gilded Age, over control of the local copper mining industry, the fight that had ramifications for not only Montana, but the United States as a whole.