Franklin Roosevelt also pardoned political allies, including Conrad Mann, who was a close associate of Kansas City political boss Tom Pendergast. Pendergast made a fortune off illegal alcohol, gambling, and graft, and helped send Harry Truman into office. Truman also misused this power, including pardoning the extremely corrupt George Caldwell, who was a state official who skimmed massive amounts of money off government projects, like a building fund for Louisiana State University.
Richard Nixon was both giver and receiver of controversial pardons. He pardoned Jimmy Hoffa after the Teamsters Union leader had pledged to support his reelection bid. Nixon himself was later pardoned by Gerald Ford, an act many of us view as a mistake. To his credit, Ronald Reagan declined to pardon the Iran Contra affair figures, but his vice president, George Bush, did so after becoming president. Despite his own alleged involvement in that scandal, Bush still pardoned those other Iran Contra figures, such as Defense Secretary Caspar Weinberger.
Bill Clinton committed some of the worst abuses of this power, including pardons for his brother Roger Clinton and his friend and business partner Susan McDougal. He also pardoned the fugitive financier Marc Rich, who evaded justice by fleeing abroad. Entirely unrepentant, Rich was a major Democratic donor, and Clinton had wiped away his convictions for fraud, tax evasion, racketeering, and illegal dealings with Iran.