Richard Nixon
Who pardoned him: Gerald Ford
What he was pardoned for: Involvement in the Watergate scandal
Why it was controversial: The Watergate scandal revealed that Nixon and his aides had not only participated in illegal activities during his re-election campaign, but they had attempted to cover it up. When Gerald Ford took office, he gave Nixon a full, unconditional pardon before he could even be indicted. The pardon was extremely controversial at the time, and widely condemned.