#3 Judge Crater
A Supreme Court Justice, Joseph F. Crater, was last seen by passers-by at a restaurant in August 1930.
After leaving the restaurant, he disappeared into thin air, and he was never heard from again.
Now, it is obvious that a man of his stature would have several enemies.
However, many speculated that he fled the country with his mistress despite his sudden disappearance and was not kidnapped or murdered.