Who is the greatest American villain?

[Rain Man]

A Charles Manson reference in another thread got me thinking about this. Who is the greatest villain in American history, the one that will draw the most ire from any right-thinking American?

Give me some options and I'll put up a poll. Nominees can come from any category: war, politics, crime, business, finance, celebrity, sports, child care, Benetton models, comic strip artists (Bil Keane, anyone?), or others. Give me your best shot.

The rules:

1. We're talking true villainy here. Villainy where you can't really defend anything the person did at a dinner party without getting winces.

2. We're talking national scale. Remember, the kicker that shall go unnamed is a hero in Indianapolis.

3. Real life only. While many may villainize Elmer Fudd for his relentless and brazen murderous stalking of Bugs Bunny, Mr. Fudd does not actually exist, and therefore any villainous acts committed by Mr. Fudd do not exist, either.

4. The villain must be an American citizen, or if their villainy took place before 1783, a resident of the area that would eventually become the United State AND acting against the United States for villainous reasons rather than sincere loyalty to another country in conflict with nascent American liberty movements or peoples and in the absence of a history of loyalty to American causes.

Once I get 20 reasonable candidates, I'll post the poll.