(This is not to be confused with Hate, the hidden number that determines which character monsters will attack.)
A threat is a weapon attack with a particularly high natural roll that might become a critical strike. A weapons threat range is listed in its critical roll information. For information on how a threat becomes a crit, see Confirming a Critical Hit.
Generating a ThreatEdit
For weapon attacks, a threat is generated whenever an attack hits, and that attack's natural roll was within that weapon's threat range. This implies that creatures with a very high AC may cause part of a weapon's threat range to be useless, if that part of the treat range would be incapable of producing a hit.
Attacking a helpless target will always generate a threat, and all threats on a helpless target will always be confirmed.