Does replacing the stock portrait images with my own in Wizardry Gold count? (note: these aren't mine). There wasn't an editor, I just replaced files in the install directory. Otherwise it was UnrealEd2 from Unreal Tournament 2003. There was so much BSP back then.
Unreal! I played it all the time at my grandparents house when I was a kid and I taught myself to make some stuff, but never really went anywhere with it, i mostly just liked feeling like I knew what I was doing.