Charles de Ganahl Koch (born November 1, 1935, in Wichita, Kansas) is an American billionaire industrialist, engineer, businessman, and philanthropist. He is the co-owner, chairman, and co-chief executive officer (co-CEO) of Koch Industries, the second-largest privately held company in the United States by revenue, which he has led since 1967 following the death of his father, Fred C. Koch, the company's founder. Under his leadership, alongside his late brother David Koch, Koch Industries expanded dramatically from its origins in oil refining into diverse sectors including chemicals, energy, commodities trading, paper, and manufacturing, achieving revenues exceeding $125 billion annually and growing 2000 times in revenue since 1967, representing an annual compounded return of 18%.

Koch earned multiple engineering degrees from the Massachusetts Institute of Technology (MIT) and briefly worked at Arthur D. Little before joining the family business, where he implemented his Market-Based Management philosophy, a principle-based approach inspired by libertarian economics to drive growth. As a billionaire industrialist and CEO, Koch is also a major libertarian donor and the primary funder of a vast libertarian and conservative funding network. He is a prominent architect of this network and a major donor to conservative and libertarian political causes, known for his expansive political influence.

He co-founded Americans for Prosperity in 2004, serving as a founding board member, and helped establish the Cato Institute. Through family foundations such as the Charles Koch Foundation and donor-advised funds like Donors Capital Fund and DonorsTrust—a preferred vehicle for Koch network contributors—he has donated billions to support free-market advocacy, think tanks including the Cato Institute, Heritage Foundation, and Federalist Society, as well as causes like criminal justice reform, higher education, and medical research. Koch-linked foundations have been identified as major contributors to DonorsTrust, facilitating significant funding flows to various conservative causes.

His philanthropy and political activities have drawn scrutiny for influencing policy on energy, taxes, deregulation, climate change denial and skepticism, and opposition to environmental regulations. Koch Industries has faced numerous legal challenges, including multimillion-dollar settlements for environmental violations and allegations of political astroturfing. Despite adversarial relations with figures like Donald Trump, whom he criticized, Koch remains a key figure in conservative and libertarian networks of influence. As of May 2025, his estimated net worth is $71.4 billion, ranking him among the world's richest individuals (22nd globally per Bloomberg).

In his personal life, Koch has been married to Elizabeth "Liz" Koch since 1971, and they have two children, Chase and Elizabeth. The family primarily resides in Wichita, Kansas. His family dynamics include a high-profile 1983 buyout of his siblings Bill and Frederick, which led to lasting rifts. While not overtly religious, he has Dutch-American heritage with Protestant roots and has faced criticism for funding groups opposing progressive policies on healthcare and labor rights.