Monster Characteristics, System Agnostic

RPG monsters tend to have a sameness about them, at least with the GMs that I've had. The monsters see you as you see them, the monsters attack, they fight to the death. If any of them flee, they cease to exist as soon as they step off stage; they don't run to bring reinforcements, set up ambushes, go tell the women and children to hide, or trail the party and try to snipe them.

Michael Prescott, on I'll See It When I Believe It, had an interesting post about what he describes as "Non-Mechanical Difficulty Levels for Monstrous Threats". If you know you're going to face a hundred orcs in an area, would you rather the orcs were all lone wolves, or trained like a Roman century?

Prescott lists several categories, although I've changed a description or two:

• Speed: immobile, slow, medium, fast
• Cohesion: hostile, rivals, neutral, fragmented, factional, cohesive, unit, gestalt
• Aggression: evasive, defensive, aggressive, predatory, ambusher
• Perceptiveness: oblivious, inattentive, alert, vigilant
• Territoriality: immobile, site-bound, territorial, regional, relentless
• Numbers: single, few, many, horde
• Lore: fully understood, familiar, unfamiliar, unknown
• Camouflage: invisible, stealthy, obvious, blatant
• Morale: panicky, fragile, firm, heroic, fanatic

If there are two dragons in an area, they might be Fast (they can fly), Hostile (they're more likely to fight each other), Aggressive, Terrritorial (if you don't poke your nose into the lair, you're reasonably safe), Alert, Single (you won't encounter more than one at a time), Fully Understood (everyone knows all about dragons, their strengths and weaknesses and motivation), Blatant (no one is in any doubt that there's a dragon around), and Panicky (once a dragon feels threatened, he's going to try to flee or negotiate).  Your orc warband (drilled as a unit, aggressive, firm morale) will feel different from your goblin tribe (factional, ambusher, vigilant, territorial, panicky).

Some of these (speed, for example) should already be built into your monster stats; adding the rest should make your monsters stand out from each other.