Notorious Monsters tend to be plot-related, quest-based, or unique to the world. They are often much stronger versions of normal monsters and beastmen. These monsters can have their own unique appearance, and some are enormous in size. Defeating some Notorious Monsters for the first time can give a Iodestone achievement.
After a Notorious Monster spawns, they must be killed in under 30 minutes. If players fail to dispatch it under the time limit, the monster will become enraged, receiving a large stat boost that tends to wipe out all players attempting to fight them. The monster will despawn after 15 minutes if it is not enraged again.
Some Notorious Monsters are Guildleve only, and don't require any chance or luck to find. They will always be present on their guildleve and can only be claimed by players undertaking that level.
Notorious monsters' strength is impossible to gauge, with their level icon displaying a ?