OSR: The Monster Overhaul: Limes and the Art of Categorization

Let's pretend you're at one of those hellish Silicon Valley lateral-thinking job interviews.

The interviewer gives you 3 categories: A: Yellow, B: Green, C: Fruit

And 6 items: 1: School Busses, 2: Grass, 3: Strawberries, 4. Lemons, 5. Limes, 6. Bananas

And tells you to sort them. Each category must contain exactly 2 items.

A: Yellow gets 1: School Busses
B: Green gets 2: Grass
C: Fruit gets 3: Strawberries

That much is trivial. The objects fit in no other category (OK, some School Busses aren't yellow, Strawberries might start off green or white, and pedants might argue that they're not fruits, but it'll do).

Lemons are Yellow and Fruits.
Limes are Green and Fruits.

And then we get to Bananas. They are Yellow and Fruits, and start off distinctly and Green. So one of the last 3 items will need to not be in Fruit, despite being a fruit. A compromise will need to be made. "Lime Green" and "Lemon Yellow" are common enough colours in English, so they might fit in those respective categories.

But if someone was told, without knowing the contents of any category, to locate Lemons or Bananas, would their first guess be correct?

Anyway, this is the problem facing the Monster Overhaul. Initial categorization is easy, but as categories are filled, the remaining categories encounter problems and compromises, far more serious compromises than Lemons and Bananas.
Art from the Hostile Forests chapter by Nadhir.

Monster Overhaul Progress Update

If you've missed previous updates, the Monster Overhaul is my next book. It's a generic, systemless monster manual designed for use at the table. It's full of tools, not text. Big fancy PDF and a big fancy hardcover... assuming everything works.

All entries in black are complete (or very nearly complete; the Dungeon chapter will be posted this week). They're available on my Patreon. You can see previews here or on twitter.

Entries in grey have some sort of draft or sketch, even if it's only a few words. The names aren't finalized. In fact, nothing about the incomplete chapters is finalized, even the titles.

9/20 chapters complete is good, but there's still a long way to go. The Dungeon chapter was the hardest one yet. It's only 23 pages long, but those pages are completely full of useful tools.

Various artists are hammering away at their respective chapters. I think giving each artist their own chapter has lead to some excellent results, but it does induce moderate anxiety; if I need to switch out a monster later, I may also need to get new art.

If you don't see a monster on this list and think it's absolutely vital I include it, leave a comment. I might already have a plan, but as the chapter fill in, the consequences of missing something critical become more dire. Monsters I'm not entirely sure about haven't been included; most chapters with grey entries have a list of 5-20 potential candidates.

1 2 3 4 5

People Sci-Fi Dungeon Dragon Primeval
1 Adventurer Alien Invader Giant Spider Kobolds Cave People
2 Barbarian Alien Visitor Goblin Wyvern Flying Dinosaur
3 Cultist Alpha Brain Lich Young Dragon Herd Dinosaur
4 Knight Doppleganger Mimic Ancient Dragon Lizard People
5 Mercenary Giant Insect Monstrous Vermin Tyrant Lizard
6 Peasant Perfect Predator Mummy

7 Pilgrim Robot Hound Myconid

8 Merchant Robot Servant Ooze

9 Townsfolk Robot Titan Orc

10 Wizard Veggie-Mite Skeleton

6 7 8 9 10

Elemental Spring Summer Fall Winter
1 Elemental Centaur Beithir Dark Fair Blizzard Eel
2 Elemental Spirit Faun / Satyr Ccoa / Raithu Dullahan Snow Golem
3 Elemental Tyrant Hateful Goose
Harvest Avatar
4 Firebat

Iron Fulmination
5 Gargoyle

6 Grue

Murderous Crows
7 Living Gem

8 Sandwalker

9 Spitling

Shofar Ram
10 Will-o-the-Wisp

Tempest Hag

11 12 13 14 15

Hot Plains Hostile Forests Mysterious Mountains Thinking Beasts Heraldic Beasts
1 Baboon Bear Ape Harpy Basilisk
2 Crocodile Boar Couatl Kappa Catoblepas
3 Elephant Dryad Giant Lamia Chimera
4 Flightless  Bird Fairy Ki-rin Lammasu Cockatrice
5 Hive Insects Giant Snake Panther Manticore Griffon
6 Hippopotamus Tiger Roc Medusa Hydra
7 Hyena Treeant
Minotaur Owlbear
8 Jinn Troll
Naga Questing Beast
9 Lion Unicorn
Peryton Strong Toad
10 Rhinoceros Wolf
Sphinx Wurm

16 17 18 19 20

Dark and Malign A Wizard Did It Water Strange Water Divine
1 Ghost Beholder Evil Icelandic Whale Tardigrade Angel
2 Ghoul Blink Dog Merfolk
Beast of Creation
3 Hag Brain Mole Pirate
4 Ogre Dispacer Beast Sea Hag
5 Vampire Golem Shark
6 Werewolf Homunculus

Greater Angel
7 Wight Rust Monster

Hell Hound
8 Zombie


Prophet / Saint

Art for the Hot Plains chapter by Lil_Tachyon

Table of Contents and the Index

There will be a "normal" Table of Contents: each chapter and entry, in order, with a page number. A useful tool to see the book at a glance, but potentially not the best tool to find a given monster (given the Lemons and Limes problem).

If you need a specific monster, the Index will be your friend. In this list, every monster in the book will appear in alphabetical order, plus every monster I can think of that could use the stats in the book. Synonyms and overlapping concepts. Ways you could potentially reflavour an entry. Obscure names, alternative spellings. I'll try to avoid setting-specific monsters, but the real world is fair game.
Art from the Thinking Beasts chapter by Lucas Roussel.

Lumpers and Splitters

Should Ape and Gorilla have separate entries? Should Sasquatch? White Four-Armed Ape of Mars? Yeti?

Or what about the dozens of half-horse-half-bird-type things. Griffons, Hippogriffs, etc. Should they get separate entries, or should they be condensed into one? I've gone with the second option.

I have to decide at what point are two creatures sufficiently different mechanically or conceptually to warrant an entirely separate entry. Just being bigger or smaller or in a different environment isn't necessarily enough. What do they do that's sufficiently different? Do they require separate tools?

The Index and other tools should help GMs find any monsters that are "missing".

Art for the Sci-Fi chapter by Frenden

Cross-References Encounters

Each chapter has 20 monsters. Each chapter also has a d10 table of "combined encounters"; a random encounter with 1 monster from the chapter and 1 monster from a different chapter. So half the monsters in each chapter will appear in their own chapter with a visting monster, the other half will visit another chapter. This lets me combine interesting ideas (Angel + Lamassu), allies or enemies (Harpy + Wind Elemental), or reflavour monsters (putting Storm Giants into the Sci-Fi chapter's combined encounter table as biomechanical war-titans).

Outside of the combined encounter tables, I've tried to minimize cross-referencing and page flipping. If a table is referenced, it's ideally on the same page, acceptably on the facing page, less optimally on the next page, or, if all else fails, elsewhere in the book. The entry for "Goblin" won't tell you to reference Treasure Table 14 on pg. 209, it'll contain a highly flavourful Goblin-specific loot table.



I'm also going to include a very compressed section on general tactics for different kinds of creatures, split into categories. Ambush Predators. Armed Warriors. etc. Including a "Tactics" section in each entry would pad the book unnecessarily, because many creatures share similar tactics.

It will probably go in the back of the book, along with a Phylogenetic Tree, The Origin of Species, alternative ways to categorize monsters, and other useful tools.


  1. Giants really ought to be split up, at least between dumb brutish hill giants and magical elemental giants. that's really two entirely separate classes of things.

    put Santa Claus in the Winter section, you coward. with workshop elves and reindeer. and gingerbread people. c'mon.

    I can't find gnomes? there should be gnomes.

    also clowns. evil clowns need to have an entry.

    there ought to be a superhero statblock or two. nothing fucks with players more than some asshole in tights and a cape shows up to protect the villagers they're trying to rob. that shit's golden.

    and what about a Jason-Voorhees-style slasher villain? although I guess that's already easy to reskin something else as...

    also maybe muppets. Electric Bastionland has muppets, maybe you should too. muppets could be the next big OSR trend. who knows.

    1. Yeah, there will be at least 2 categories of Giant.
      Not exactly sure how to make Santa Claus work... but that jolly old elf is on the shortlist.
      Gnomes, I rolled into Fairy.
      Evil Clowns... well, I've got the Dark Fair for the carnival-of-horrors aspect, but there might be another place where they'd fit.
      The Superhero idea is interesting. I think reflavouring the Perfect Predator statblock could work... though I'm not sure how to integrate that outside of the Index. Hrm.
      Slasher Villains are also covered by the Perfect Predator, or maybe Minotaurs/Ogres.
      Muppets... hrm... more thinking. They could fit somewhere, but where? And why?

    2. superheroes: move the Dopplegangers out of sci-fi and into Dark & Malign, maybe, and put them there?

      or: combine the "water" and "strange water" categories (why the fuck are they two different categories anyway???), and create a new category... "Saturday Morning Gonzo," maybe? get Muppets in there, get superheroes in there, you could get Transformers in there, you could get some kind of Pokemon in there, right? just a repository of things you could inject to really spice up and fuck up a campaign world.

    3. Doppelgangers have a lot Sci-Fi variants: Westworld robots, Replicants, the Thing, etc.
      "Strange Water" is for microfauna made large.

    4. eh, still, feels like Doppelgangers are just as viable outside sci-fi as in it. doesn't seem like the intuitive place for them to me. idk lol

      and ok "strange water" makes a lot more sense now! I'm curious why you need ten entries of those but I am prepared to be amazed lmao

      maybe put muppets under Thinking Beasts? after all, what are Muppets: they're showmen, they're performers, they're a lot of fuzzy felt-skinned bards. they do more thinking than the average Minotaur seems to, anyway.

      or they could go under "a wizard did it." because we know Jim Henson was basically a wizard anyway, right? idk.

  2. Looking forward to seeing it finished! I'm quite intrigued by the difference between a Tempest Hag from (9) and the regular Hag from (16), or the Wyvern from (4) and the Wurm from (15).

    1. Tempest Hag flies via balloon/greased pig/etc and deals out minor curses. Regular Hag bakes kids into pies and stirs a big cauldron. Etc.
      Wyverns fly. Still not quite sure what else I want to do with it. Wurm covers not only the famous Purple Worm, but Red, Orange, Yellow... Worms as well. All with their own twist.

  3. Ghost will include things like wraith, banshees and other incorporeals?

    Kraken? Rakshasa? Yokai? Siren/Selkie? Will o Wisp? Behemoth/Tarraque/VeryLargeCreature?

    1. Ghosts: Wraiths yes, not sure about Banshees yet.
      Kraken: should be in.
      Rakshasa: probably folded into one of the Divine categories.
      Will-o-Wisp: is in Elemental.
      Yokai is a very broad category; a lot of things in the book could be different yokai.
      Behemoth/Tarrasque/Leviathan/etc. goes in Divine, under Beasts of Creation.

    2. Sirens are folded into Harpies.

    3. Nice!

      What about arthropodes with exoskeleton and claw like crabs, lobsters, scorpions, centipedes, etc?

      And carnivorous fishes that aren't sharks like piranhas? Maybe another entry for that uncatchable fish all fishers talk about, just use your your favorite fish like pirarucu, grouper, barracuda, pike, etc.

      Flameskull? That classic flying skull in flames that explodes when it dies.

      Succubus is technically a demon but it may be just a demon skinned harpy, lamia or whatever.

    4. Giant Enemy Crab is on the shortlist.
      Flameskulls are covered by Firebats in Elemental, but I'll add a note to reflavour them in the Dungeon chapter cross-ref. encounter table or index.

  4. Dragons: Oriental dragon and slavic three-headed dragon, maybe amphisbaena?
    Winter: Jack Frost or some other ice spirit, winterwolves? The Others from ASOIAF?
    I don't see lovecraftian horrors, are you going to put them in "strange waters" or you plan to reflavour monsters you already have?
    I propose to rename the tardigrade "tarGigade"

    I love this project and I'm looking forward to see it finished!

    1. Yeah, not quite set on how to divvy up the 10 Dragon slots. Many options.
      Lovecraftian Horrors: honestly, a lot of existing creatures can be reskinned instead of entirely new rules.

  5. Water/Strange water:
    * Giant Octopus (grabby, camouflagey, possibly intelligent, a pulp staple)
    * Island Fish (monster that is also a location)

    But maybe just combine them into Water? The division seems blurry in a fantasy setting. Then you could open up another category, maybe Urban? Urban could have assassins, trades (more as a way to talk about gameable things from professions, like the medieval miners you wrote about before), hirelings/mercenaries, wererats...

    Also, dragons:
    * Crossbreeds
    * Cultists
    * Dracolich
    * Lairs

    1. I'd like to keep one section for aquatic creatures that might make you go "Hang on, what?" in a standard D&D-type game.
      I thought about doing an Urban category, but it ended up being a sort of setting-in-miniature. Didn't really work out as a chapter. Plus, Magical Industrial Revolution has a bunch of urban tools I'd need to reprint.

      At least 2 Lairs will be in the Dragon chapter. Dracolich is a good call.

    2. That makes sense. The Burgess Shale fauna should offer some good "strange water" fodder.

      Under dragons, "slayers" or "would-be" slayers could fit in some NPCs and/or dragon-specific magic items.

      If fall has "dark fair", you could have some corresponding fertility festival for spring? Wickermen, things bred for sacrifice - mentioned Pan is on the shortlist. Or maybe this is summer stuff.

      And it might be too late if you've got artists going on each chapter already, but what about switching the categories for Owlbear and Unicorn?

    3. Yup, I might do a "Not Another Phylum"-style Arthropod generator. Just for kicks.
      Dragons... I hadn't considered Dragon-Slayers as an entry, separate from Adventurers. May not work it. Magic items, ingredients, etc. will be in there of course.
      Good call on a Wickerman-type-thing; could either be a cross-reference to Giant or its own entry. Harvest Avatar has some aspects of that as well.
      I think Unicorns are pretty much only associated with Forests, while Owlbears turn up all over the place, so I'm happy with their locations, even if heraldic unicorns are more common.

  6. Interesting stuff. These are the exact details i was hoping to find out about this project.
    You have Snow Golem under #10 and Golem under #17. Do they merit different entries? If you want to be real hip you can make your Vampire entry into a "Vampyr" and get weird with it.

    When asking the question, "would their first guess be correct?" The only answer I see "no" to is Kobold and Crocodile. Personally, my first guess for croc would be to look in a River category, seeing that's absent, I would look int Water. I would also be unsure what creatures would fall under the seasonal categories, but as-is they seem to fit.

    1. I think Snow Golems are lower HD creations closer to Frosty the Snowman, but it's not definite.
      Vampires will have lots and lots of tools. Modern, Stoker, folkloric, etc. Many variants, same basic rules.
      Kobolds are draconic these days. It's just how it goes.
      A separate River section didn't really work; too much overlap with a full Sea section, not enough river-specific stuff.

  7. wait a second you need a pseudodragon!!! under the dragon section!!!

    also probably a mammoth and an aboleth under the primeval section, that's where I'd look for both of those.

    also... aren't wotc protective as fuck of the Beholder copyright? but if you circumvent that somehow lol you should also include a smaller beholder, like the 5e Gazer, that's suitable for a wizard to have as a familiar, that shit's dope.

    1. Mammoth could just be a reskinned Elephant.
      Interesting choice on Aboleth in Primeval. Makes sense though.
      It won't be named Beholder, of course, but it's dangerously close to becoming like velcro (or heroin).

  8. ok I'm gonna keep coming back here when I think of more shit:

    EASTER BUNNY for spring!!! also sentient marshmallow chicks! also maybe a literal fertility goddess or something, just yeet Ostara in there.

    sentient chess pieces / playing cards!

    crawling claws are always good, and other scraps of reanimated flesh-- a giant's rotting intestines, slithering along, strangling people, shit like that.

    animated armor / swords / shields! include an animated flaming sword like the one that guards Eden??? could be cool

    and if you wanna go a little meta... maybe stat up 5e-style murderhobos for OSR characters to fight against? maybe that's already covered under the "adventurer" tab but a separate heading for all the min-maxed half-elf hexblade/paladin multiclass weirdos could be a nice touch.

    1. Easter Bunny / Ostara / Bacchus / Pan / Spring Deity type thing is on the shortlist.
      Oh dear, marshmallow chicks.
      Not entirely sure chess pieces or playing cards wouldn't be better as setting/module specific reskins. How often do they come up?
      Crawling Claws, yes.
      Animated Armour is a tricky one. It's got a lot of similarities with Iron Golems in some ways. And how do you "kill" one anyway?
      "Adventurer" definitely covers your typical party.

    2. an animated armor is sort of like an iron golem, but including a flying slashing sword under golem seems like a helluva stretch lol.
      and they could be killed one of three ways, I guess: either just damaging its integrity a bit is enough to dispel the enchantment (think: hitting a floating sword with a sledgehammer and it gets dented and falls to the ground, hooray!) OR its animation is granted by a separate magical talisman somewhere nearby, destroy that and the enchantment's dispelled OR these things just can't be killed, per se, but they could be immobilized or otherwise rendered impotent through anything that would make a regular weapon useless: trap the flying sword under a pile of rubble, or immobilize it in a column of ice, or a white-hot firebolt melts the sword to a puddle of shimmering slag that still twitches impotently on the dungeon floor. makes sense if you think about it.

      and idk about the chess pieces / playing cards. If you put them in the bestiary, they'll see use, that's how bestiaries work, right? I don't think I've thought of using an "evil icelandic whale" in an adventure but if you put it there it could be legit. they're definitely USEFUL, filling the same "bound by obtuse logical rules" role that Modrons sometimes do, but in a more whimsical, less "Established D&D"-y way.

      put marshmallow chicks in, you coward

    3. I can roll Animated Armour, Animated Swords, Chess Pieces, and Muppets (as Animated Puppets) into one category in "A Wizard Did It". Same approximate HD. Huzzah.

    4. huh, that actually hella works. they do clump together nicely, guess this is why you're the bestselling osr author and I'm the anonymous internet schmuck. helluva mood.

    5. Nah, it's all a matter of thinking and testing and thinking some more. :D There's no secret sauce, just time, effort, and learning from mistakes.

  9. Phoenix probably best belongs in Spring or Summer (Spring being Renewal from death, Summer because hot).

    Yuki-onna could be added to Winter, if there's trouble filling out that section, as could Winter Wolf.

    Lots of "Ghost" type things could fit under dark and malign, but every addition of a spectral spirit detracts from the possibilities for Ghost. Banshee comes to mind as one that might be appropriate for separating out.

    Stirge might belong in Summer as a last thing remaining, as a replacement for mosquitoes.

    Ants, Bees, and Termites (Giant or otherwise) might be appropriate for Spring or Summer. Something about breaking open hives to get at something valuable is appealing.

    1. Phoenix has appeared and disappeared from this list a few times. It's thematic, but does it really need stats?
      Yuki-onna is a good one.
      Stirges too have a few options. They might be best represented under Murderous Crows.
      I think various insects, between the Colossal Insect in Sci-Fi, the Hive Insect in Hot Plains, and the Monstrous Vermin in dungeon, have things well covered.

    2. you could combine the phoenix with, like, the Slavic Firebird, to make it more gameable...

  10. I have some recommendations for your Strange Waters:

    1. Rotifer: Ambush predators with suction mouths. Steals genes from the creatures it eats.
    2. Krill: They're the dominant animal life-form on the planet. How can you have a dozen or so humans but not even a single Krill? They also have illusion powers and can eject their exoskeletons to act as a decoy.
    3. Placozoa. The simplest animals. Like if a scrap of skin gained independence.
    4. Difflugia. Amoeba that builds a big round shell out of stuff it finds. Looks kinda like a shuckle from pokemon. Surprisingly agile.
    5. Planarians. Just because they're cute. They do also have fantastical regenerative abilities.
    6. Egg. Egg is a classic monster.
    7. Skeleton Shrimp: Shaped a a creepy disembodied skeleton hand.

  11. Some ideas:

    If not already included under ghost/dybbuk/brain mole, some sort of mind/body-controlling parasite or spirit

    Some sort of genius loci or living location (or is this dark fair reskin?)

    A Goblin Punchy druid could be a meaningfully distinct category from cultist in one of the seasonal categories

    Some kind of monster that's so big that parts of it are statted as individual monsters (unless already included under ancient dragon/giant/beast of creation)

    Is charybdis/giant antlion/sarlaac/kirby a monster archetype? For a monster whose gimmick is sucking you in

    Zaratan (under evil whale?)

    Maenads/mob/formation, swarm of people sized/shaped creatures

    Bogeyman/bugbear usefully distinct? Sneaky, hides in disproportionately small places, weird alternate dimension in closets/darkness?

    Green Knight-ish fairy knight? Rolled under knight/dullahan?

    Cursed doll/grimoire with teeth/evil magical objects in general?

  12. Mysterious mountains should include a yeti/bigfoot and hawk people.

  13. kinda missed the bus here, but switching out greater angel for archon might bear fruit, not necessarily because greater angels are archons but it bring sin some more neutrally-flavored gnostic influences into a list that seems to be pretty classic judeo-christian

    1. No worries. The final list ended up being:
      1. Angel
      2. Beast of Creation
      3. Cherub
      4. Demigod
      5. Devil
      6. Dybuk
      7. Hell Hound
      8. Imp
      9. Scapegoat
      10. Visionary