Third-party

Other (objects, etc.) concept

There's an extra person, group, organization, or something that takes somewhat active role in the depicted events but is not really part of them (steers clear of any conflicts if possible, does not challenge either of the ones fighting).

These are commonly an organized neutral NPC faction that avoids conflict with the main players, but still pops up often enough that they're notable and may actually offer some services to one or both of the sides.

These may occasionally oppose either, but not for anything the overall conflict is about.

Most likely reasons for their existence is to give depth to the world you're playing in.