The Copper Kings - William Clark, Marcus Daly, and Augustus Heinze - were industrialists who made fortunes in the late 1800s through early 1900s from copper mining in Butte, Montana. They used their wealth to build up infrastructure like newspapers, banks, and courts to gain power over their rivals. Their mining operations created many jobs and drove economic growth in Montana, though it also displaced local Native American tribes. Over time, their individual mining interests consolidated into larger monopolies like Amalgamated Copper and Anaconda Copper, transforming Montana's economy.