X-risk

Suppose also that you think AI is the most pressing x-risk, because (1) mitigating AI risk could mitigate all other existential risks, but not vice-versa, and because (2) AI is plausibly the first existential risk that will occur.

Source: wiktionary

There are a number of potential candidates for most threatening X-risk. Personally I worry most about global pandemics, both because things like the Black Death and the Spanish flu have caused massive death before, and because globalization and the dawn of synthetic biology have made diseases both easier to spread and easier to tweak (intentionally or not) for maximum lethality. But I'm in the minority on that. The only X-risk basically anyone wanted to talk about at the conference was artificial intelligence.

Source: wiktionary