Various risks exist for mankind and civilization, but not all risks are equal. Risks can be roughly categorized into six types based on the scope of the risk (Personal, Regional, Global) and the intensity of the risk (Endurable or Terminal).
The risks in this list are associated with those in the Global-Terminal category. This type of risk is one where an adverse outcome would either annihilate intelligent life, or permanently and drastically curtail its potential. It is a risk where humankind as a whole is imperiled and/or would have major adverse consequences for the course of human civilization.
Various scenarios for the extinction of the human species have originated from science, popular culture, science fiction, and religion. There are many potential end-of-civilization scenarios that have been suggested could happen in the future. Some are far more possible than others; listed here are the most well known.
Intervention by a God or gods