The man who shot Theodore Roosevelt in Milwaukee in 1912, during his campaign against William Howard Taft and Woodrow Wilson for the presidency (which Roosevelt subsequently lost).
John Schrank was a psychotic New York bar owner who had supposedly shot Roosevelt because of a dream he had had. He told an interviewer "I saw President McKinley sit up in his coffin pointing at man in monk's attire in whom I recognized Theodore Roosevelt. The dead president said, 'This is my murderer, avenge my death.'"
Schrank shot Roosevelt at close range with a .38 caliber pistol. Roosevelt's survival seems incredibly lucky - he had the notes for a very long (50-page) speech in his coat pocket, folded in two, which slowed the bullet. Behind that, he had a steel spectacle case. The bullet did pass through both of these, but by the time it entered Roosevelt's body, it didn't have enough speed left to do any substantial physical damage. In fact, Roosevelt was well enough to give his speech before seeing a doctor, and the bullet was never removed.
Schrank finished his life in a state hospital in Wisconsin (he died in 1943 at the age of 67), never having been tried for the assassination attempt.