The world is full of mysterious men that have made an impact on history, people who have followed a secretive lifestyle and died with unanswered questions about their true motivations. In many cases, these people are top secret spies, psychics, serial killers, government scientists, mafia members, assassins, or whistle blowers. The individuals have all been tainted by bizarre accusations and unsubstantiated claims. In response, conspiracy theories have emerged to describe the events. Here we examine the lives of 10 mysterious men that continue to fascinate people around the world.