Which man held a monopoly in the oil industry?

John D. Rockefeller is the man most famously associated with holding a monopoly in the oil industry. Through his company, Standard Oil, founded in 1870, he controlled a significant portion of the oil refining and distribution in the United States by the late 19th century. His business practices, which included aggressive pricing and consolidation of smaller companies, led to the eventual breakup of Standard Oil in 1911 under antitrust laws.