NPCs are everywhere.EVERYWHERE! Every monument has NPCs (except Fishing Village, Abandoned Cabins, and Steamhaven). Yes, there are hostile NPC’s at lighthouse, mining outpost, abandoned supermarket, Oxum’s Gas Station, all the Quarries, and increased at all the normal monuments.
You may even run into Fredrick, the wandering roadside scientist or Charles, the wandering Heavy Scientist.
NPCs also spawn with some of the events, like Sputnik, Zeppelin Cargo Crash, Convoy, Road Bradley, and others. In addition, extra NPCs spawn during vanilla events: patrol helicopter, Bradley, and crates dropped by chinook. Stay alert! Air drops are the exception and are safe-ish.