Brains.

Everyone knows Abraham Lincoln was a vampire hunter, but did you know he wasn't the only president with such tendencies?

James K. Polk hunted werewolves.

Theodore Roosevelt drove the chupacabras south of the Rio Grande.

John Adams fought Victor Frankenstein.

Calvin Coolidge punched a mummy in the face.

Grover Cleveland defeated alien invasions on two non-consecutive occasions.

John Quincy Adams fought Victor Quincy Frankenstein.

And of course Zombie Richard Nixon betrayed and killed Zombie Spiro Agnew.