The New Yorker was the first to report David Koch's death Friday morning.
David Koch and his brother were well-known for their support of conservative and libertarian causes, using their vast wealth to reshape American politics, The Wall Street Journal reported. Together they founded the anti-tax, small government group Americans for Prosperity. In 1980, David Koch was the vice presidential candidate for the Libertarian Party.
David Koch also used more than $1 billion of his fortune, which Forbes estimated to be around $50.5 billion, to contribute to philanthropic causes, The New Yorker reported. The Smithsonian's National Museum of Natural History named in his honor a wing dedicated to the story of human evolution after he donated $15 million to fund the 15,000 square-foot hall. He donated $100 million in 2007 to create the David H. Koch Institute for Integrative Cancer Research at the Massachusetts Institute of Technology.
"He believed he had a responsibility to a world that had given him so many opportunities to succeed," David Koch's family said Friday in a statement. "David's philanthropic dedication to education, the arts and cancer research will have a lasting impact on innumerable lives -- and that we will cherish forever."
David Koch, an engineer trained at MIT, joined Koch Industries in 1970, and served on its board. He also served as chief executive officer of Koch Chemical Technology Group, LLC, a Koch subsidiary.
Due to declining health, Koch stepped down last year as vice president at Koch Industries, according to NBC News and The Washington Post.
He was diagnosed nearly three decades ago with advanced prostate cancer. Charles Koch said Friday that his brother was told he'd have only a few years to live.
"David liked to say that a combination of brilliant doctors, state-of-the-art medications and his own stubbornness kept the cancer at bay," Charles Koch said Friday. "We can all be grateful that it did, because he was able to touch so many more lives as a result."
David Koch is survived by his wife, Julia Koch, and three children.
"While we mourn the loss of our hero, we remember his iconic laugher, insatiable curiosity and gentle heart," his family said Friday. "We will miss the fifth link in our family."
The Associated Press contributed to this report.