Warren Buffett and Bill Gates were able to line up more than $100 billion in charity pledges from the American elite, but many of the richest in the U.S. haven't take the pledge to donate a majority of their assets to charity. Click here to see the billionaries who are also rich in the giving spirit.
NET WORTH: $11 billion The controversial history of the corporate raiders turned capitalist do-gooders was also reflected well in the tie at No. 4, with the biggest of the billionaires joining the Buffett/Gates group on Dec. 8 being corporate raider Carl Icahn and his $11 billion fortune. Icahn's $11 billion placed him in the tie at No. 4 with original Buffett/Gates pledger Perelman. Michael Milken, arguably the most famous figure from the 1980s era of corporate raiders, also joined the Buffett/Gates group of big-hearted billionaires, pledging a majority of his $2.1 billion fortune to charity. Milken has long since reformed from his days as the junk bond king and has been a major philanthropist and think tank backer through his Milken Institute, and the Milken Family Foundation, which he founded in 1982. While Milken is primarily focused on his far flung and deep-thinking ventures in economic policy, medical research and philanthropy, Icahn is still battling it out for control of troubled companies. Icahn was a major player in the battle for control of bankrupt video chain giant Blockbuster, and is now engaged in the fight over the future of the Lion's Gate Entertainment-MGM merger plans.