Historical Figure: J. Edgar Hoover
What He's Remembered For
Hoover headed the FBI through eight presidential administrations, helped out during the Depression and World War II and received several awards including an honorary knighthood from King George VI.
Why You Should Hate Him
Most people already hate J. Edgar, so perhaps it would be more important to explain why else you should hate him: He told Dr. Martin Luther King Jr. to kill himself.
Hoover once asked to meet with Dr. King for lunch, and King refused. Apparently, Hoover was so furious that he made it his mission to destroy his career and life. He sent a package to Dr. King's house in which he politely requested that, in 34 days, he kill himself or else. King, just as politely, declined.
Once King was assassinated, Hoover and his cronies started rumors that the shooter was the husband of one of King's many, many mistresses. To add insult to injury, Hoover presumably did all of this while wearing a sundress.
The country was so disgusted with his behavior that President Lyndon B. Johnson decided to let Hoover continue serving in his incredibly influential and well-paid position as head of the FBI, despite having reached the mandatory retirement age.
Honorable Mention: Lyndon B. Johnson (see above)