3. Bioengineered pandemic
Natural pandemics kill more people than wars and violence. However, there is very little chance of a natural pandemic wiping out all of humanity. There will always be some people who are resistant to the disease who will survive. On the other hand, thanks to advances in biotechnology, humans can make illnesses much more potent. There will always be a group of people who will try to use biological weapons to further their cause and certain cults have even attempted this in the past. Even governments experiment with controllable biological warfare. Although we these attacks have a few victims; deliberate, man-made pandemics have the potential to be catastrophic to the human race.