Level 0: Skin Stealers and Dollface
Level 0 (Nightmare and Hardcore Mode) Dullers and Dollface
Secret Halloween Event: Corrupted Partypooper (Hasonpooper), The Cloaked Man and The Gateman
E6621275 Event: E6621275, Ben and Memory
Level 1: Necker/Rokurokubi
Level 2: Hound and Faceling
Level 3: Dullers, Clumps and Faceling.
Level 4: Kesseki
Level 4 (EX Mode and Hardcore Mode): Hound
Level 4 (Nightmare Mode) Facelings, Kesseki and Hound
Level 5: The Beast of Level 5
Level 6 (both modes): Smilers
Level 7: The Beast of Level 7 (only appears in the run scene)
Level FUN =): Partygoers
Level 8: Spiders and Clumps
Level 9: Sadako and Smilers
Level 10: N/A
Level 11: Facelings and Hounds (all of them are friendly npcs because of the 11 effect)
Level 12: N/A
Level 13: N/A
Level 14; Clumps
More coming soon!