There were, of course, many important industrialists during this period. One important industrialist, and the one who amassed the most wealth during the period, was John D. Rockefeller, who built Standard Oil Company of Ohio into one of the largest and most powerful trusts in the United States.
Another was Andrew Carnegie, who cornered a massive share of the steel industry for his firm, Carnegie Steel through innovations in vertical and horizontal consolidation. He amassed an even greater fortune when he sold his firm to investor J.P. Morgan.
George Pullman built a massive fortune manufacturing railroad cars, specifically the sleeping cars that bore his name. His plant outside of Chicago was the centerpiece of what was held to be a model manufacturing town, with all of his workers living on site. However the town, named for Pullman himself, fell with a serious and bloody strike in 1894.
Leland Stanford was perhaps the most successful magnate in one of the major growth industries of the period, the railroad industry. Stanford was owner of several major railroad lines in the West, and was responsible for the western half of the transcontinental railroad.
Finally, another massively successful industrialist was James Duke, who industrialized the manufacture of smoking tobacco, particularly cigarettes. His American Tobacco Company was the largest in the United States, and he had a monopoly in the sale of tobacco to the British Empire. Like many of these industrialists, Duke diversified his holdings, gaining a monopoly of electricity in North Carolina. Also like many industrialists, Duke devoted much of his wealth to philanthropy, with much of his wealth going to Duke University.