What robber baron became one of the wealthiest people in the world by creating a trust that controlled most of the oil refineries in the US?

John D. Rockefeller became one of the wealthiest individuals in history by founding Standard Oil Company, which established a trust that controlled a significant portion of the oil refineries in the United States. Through aggressive business practices, including horizontal integration, he was able to dominate the oil industry and reduce competition. His wealth and influence made him a prominent figure in the era of the "robber barons" during the late 19th and early 20th centuries.