Julia Margaret Flesher Koch (born April 12, 1962) is an American socialite and philanthropist who is one of the richest women in the world.

[9][10][11] McCarthy said she was "one of those people who occur in New York every few years...she's beautiful, she loves fashion, she knows how to entertain, she's married to an extraordinarily rich man.

[18] In 2022, Koch put the apartment at 740 Park Avenue on the market; a spokesperson said that she wanted to sell it because she was spending more time at houses in Southampton and Palm Beach.

[19] She also established the Julia Koch Family Foundation, which donates to healthcare, educational and cultural organizations.

[25] In 2012, Koch made a $10 million gift to the Mount Sinai Medical Center in New York City, creating the David H. and Julia Koch Research Program in Food Allergy Therapeutics within its Jaffe Food Allergy Institute.

[26] In 2016, she donated $10 million to establish the David & Julia Koch research clinic for allergy and asthma at the Lucile Packard Children's Hospital at Stanford University.

[28] Roy I. Davidovitch is the current Julia Koch Associate Professor of Orthopedic Surgery and director of NYU Langone's Hip Center.