Julia Margaret Flesher Koch is an American businesswoman and philanthropist, the billionaire widow of David H. Koch (d. 2019) and one of the wealthiest women in the world. Her colossal wealth stems from her inherited 42 percent stake in Koch Industries, the largest privately owned company in the United States (spanning chemicals, energy, refining, and manufacturing).

Julia's career is defined by her generational stewardship of the family's assets and her immense philanthropic commitment to the arts and medical research. Her family relocated from Iowa to Arkansas and later to New York City. Before marrying David Koch in 1996, Julia worked as a fashion assistant to designer Adolfo, and she met David Koch at a blind date in 1991.

• Koch Industries (Co-owner): The core private asset, the largest privately owned company in the U.S. (controlling 42 percent of the company). The company's revenue is estimated at $130 billion (2024 estimate).
• Philanthropy: She is a trustee of the Metropolitan Museum of Art (Met) and committed $10 million for the Julia F. Koch Gallery at the Metropolitan Museum.
• Social Focus: Her career is tied to the social and cultural elite of New York City.
• Political Ties: Her late husband was a prominent Republican donor who led the Koch political network.

Julia Koch's structural role is primarily tied to the fiduciary oversight of her massive inheritance in Koch Industries and the Koch family's political network. Her late husband, David Koch, was a key executive alongside his brother, Charles Koch, who still serves as Chairman and CEO. Julia's wealth is secured by the colossal, long-term, stable profitability of the global industrial and energy sectors.

Her most visible structural contribution is in arts and cultural philanthropy: she serves as a Trustee of the Metropolitan Museum of Art (Met) and has made massive donations to the institution. She also supports medical research and educational initiatives. Her challenge is managing her family's stake in one of the world's most powerful, but politically controversial, private companies.

Julia Koch's social impact is massive and structural, tied to Koch Industries' role as a foundational provider of essential chemicals, energy, and industrial materials globally. Her profound philanthropic contribution to the Met ($10 million gift) and other cultural institutions provides a major structural contribution to U.S. arts and culture.

Her structural contribution is tied to the Koch family's political network, which spends hundreds of millions of dollars annually influencing conservative and libertarian policy across the U.S.

Julia Koch maintains the elegant, high-profile style of a New York socialite and philanthropist. Her attire is consistently bespoke and high-quality, favoring designer wear. Her aesthetic reflects immense wealth and profound cultural influence, typical of a leader in New York's philanthropic and social elite.

Residing in New York City (with a massive, exclusive Fifth Avenue apartment), her luxury is the immense security and financial reward derived from her multi-billion dollar fortune. Her life is dedicated to philanthropy, social engagement, and the stewardship of the Koch industrial legacy.