How many people have seen the Lone Ranger unmasked?

According to this website: http://weirdscifi.ratiosemper.com/loneranger/faq.html three or four people have seen the Lone Ranger unmasked: Tonto, his nephew and his Grandmother. And maybe Butch Cavadish, depending on if you go by radio or TV. However, a recent public radio interview had a Lone Ranger historian who claimed it was these three people: Tonto, his nephew and President Ulysses S. Grant. Which is correct?