AI doomsday scenarios are worst-case ideas about advanced AI causing severe, possibly irreversible harm. In practice, the term covers a range of high-impact failures: a model used for large-scale abuse, systems acting in unintended ways after deployment, or future AI becoming difficult to control as autonomy increases. These scenarios are not proof that catastrophe is likely; they are a way to think about low-probability, extreme-consequence risk.
In cyber security, the term matters because defenders must judge what happens when AI is used offensively or when AI itself becomes part of critical infrastructure. Security teams respond with capability evaluations, red-teaming, access controls, staged rollouts, monitoring, and human approval for sensitive actions. The goal is to detect dangerous behavior early, limit misuse, and keep advanced systems governable before they are widely deployed.