Originally posted by Cooperal:

Just to clarify further about non-respawning enemies, the ones that do not respawn are attached to a generated structure like a ruin, dungeon entrance or dungeon interior.

For example the burial chambers in black forests typically generate with a small arrangement of skeletons guarding the entrance. If you kill these ones they will never come back. It can be a bit difficult to notice this right away because enemies that spawn like this are indistinguishable from their randomly roaming equivalents in every other way.

Thanks, thats minor and not an issue, I just didnt want to take out spawners if it meant an area would always then be barren of mobs, although, I went to a burial chamber in the black forest that I had marked and killed the mobs outside, yet there was still one solitary skeleton again outside, couldve been a random spawn of course or one I had missed previously