As creative as always, Streamer Blurbs has made a Fallout 4 mod that adds a cheap cardboard cutout of Todd Howard, which slowly stalks players across the map with murderous intent, an idea inspired by suggestions from his subscribers. And to make things even more terrifying, you can't kill him.
That's just one of many ideas: in his video, you can also see mods featuring giant, rad-looking roaches (optional), a mod that makes you trip and spill ammo and caps, randomly appearing Preston Garvey to scare you, and randomly exploding NPCs: