Ultima IV: Quest of the Avatar/Enemies

Stronger enemies appear as the Stranger gains experience levels.

If a non-evil enemy is killed, the Stranger loses virtue points. Carry a stock of slings, in order to weaken such enemies without killing them, until they flee. Also, you can flee from non-evil enemies without losing virtue. In some ports, the game acts a bit odd in regards to non-evil creatures, sometimes inconsistent (e.g. lost valor for fleeing from non-evil, or taking no penalty for killing in an already started combat) as if the mechanic includes more complex, hidden variables (or just a small bug).

In the NES remake, the distiction between evil, undead, and non-evil enemies was omitted: the companions should defeat all enemies, and never flee.

The sprites for the MS-DOS are similar to those for Amiga & Atari ST, but with slightly different colors.

Land enemies
Undead enemies will flee when the "Undead spell" is successfully cast. This spell was omitted from the NES remake.

The NES-only "Reflect" spell fully protects from the physical ranged attacks by Trolls, Ettins, and Cyclops (as well as sea Nixies).

Sea enemies
Sea enemies leave no gold after combat. Pirates leave their ship.

Pirate ships start appearing when the Stranger reaches level 4 (800 experience points).

Dungeon enemies
Reapers become harmless if the companions cast the "Negate" spell.

In the NES remake, all enemies can move. Also, enemies labeled as "non-evil" only appear when the party is at a low experience level (i.e. they disappear before the party is ready to brave the dungeons).