David Hamilton Koch (3 May 1940 – 23 August 2019) was an American multi-billionaire chemical businessman and libertarian political activist. The twin brother of Bill Koch, they ran their family business, Koch Industries, from 1970 onwards, and David served as executive vice president until his retirement in 2018. In 1980, he was the US Libertarian Party's vice-presidential nominee, and he later founded Citizens for a Sound Economy and became a major Republican donor and Tea Party activist. He was also a major philanthropist, and, in 2008, the New York State Theater, home to the City Ballet, was renamed the "David H. Koch Theater". In 2013, he was the wealthiest resident of New York, and, by June 2019, he had a net worth of $48 billion. He died in August 2019 at the age of 79.