David Hamilton Koch (; May 3, 1940 – August 23, 2019) was an American businessman, philanthropist, political activist, and chemical engineer. He joined the family business Koch Industries, the second-largest privately held company in the United States, in 1970. He became president of the subsidiary Koch Engineering in 1979, and he became a co-owner of Koch Industries, with elder brother Charles, in 1983. He served as an executive vice president until his retirement in 2018. Upon retirement in June 2018 due to health issues, Koch received the title of director emeritus.
Koch was a libertarian. He was the 1980 Libertarian candidate for Vice President of the United States and helped finance the campaign. He founded Citizens for a Sound Economy. He donated to political advocacy groups and to political campaigns, almost entirely Republican. He moved to the Republican Party in 1984; in 2012 he spent over $100 million to oppose the re-election of President Barack Obama.As of June 2019, he was ranked as the 11th-richest person in the world (tied with his brother Charles), with a fortune of $50.5 billion. Koch contributed to several charities including Lincoln Center, Sloan Kettering, NewYork–Presbyterian Hospital, and the Dinosaur Wing at the American Museum of Natural History. The New York State Theater at Lincoln Center, home of the New York City Ballet, was renamed the David H. Koch Theater in 2008 following a gift of $100 million for the renovation of the theater. Koch was the fourth richest person in the US as of 2012 and the wealthiest resident of New York City as of 2013.
He is also known as David Hamilton Koch and David Koch.