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CASTLE OLDSKULL - Oldskull Monster Generator


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The OLDSKULL MONSTER GENERATOR is the ultimate random monster creation tool, created specifically for both the Fifth and First Editions (5E, 1E) of the world’s first and foremost Fantasy Role-Playing Game (FRPG).  Rules and guidelines are provided for both editions.

This colossal page compendium contains the largest, most comprehensive, and most ambitious monster creation system ever devised.  If you feel that your game might be suffering from a lack of variety in monsters and encounters; if you want straightforward help and guidance in refining your own monster concepts; or, if you just want to inject some old school Gygax-inspired, Arnesonian, and Lovecraftian atmosphere into your modern FRPG, then this is the perfect resource for you.  Tap into the chaos, fear and madness of the Elder Things to animate, twitch and galvanize your game!

The OLDSKULL MONSTER GENERATOR is actually a complex set of interrelated monster customization systems.  These systems follow the unifying principle of guided randomness, ensuring that your monster is otherworldly, but also that it makes sense and fits perfectly into your structured game world.  You can selectively pick and choose from the worksheets and various tools provided herein to supplement your own unique method of monster design.  Or, you can enjoy a guided and example-driven mentorship approach, which will lead you through all of the principles of monster creation, encounter development, and campaign integration from beginning to end.

Herein, to assist the harried Game Master (GM), you will find:


  • POWER:  Complete rules for creating any kind of monster (Abomination), from CR 0 to 30 (or old school monster levels I to X).  The variety of the monsters you can create is virtually infinite.
  • OPTIONS:  Over 260 articulated Abomination body types to inspire your brainstorming and the creation of ever more bizarre monstrosities.  Everything from worms to octopi to centaurs are included.
  • ARSENALS:  Nearly 700 unique monster abilities, quirks, and vulnerabilities, arranged into 30 monstrous themes, from Acidic to Water / Aquatic and everything in between.
  • MATRICES:  Interconnected systems to generate monster descriptions, senses, languages, alignment, movement, ability scores, hit points, armor class, and basic and special attacks.  All you need are percentile dice and imagination.
  • CULTISTS AND MADMEN:  Extensive guidelines for monster summoners, binders, worshippers, cultists, and minions.
  • NEW HORIZONS:  Suggested rules for monstrous events including otherworldly rituals, madness, parley, trophy harvesting, adventurer resurrection, and journeys to the campaign-widening Dream Worlds.
  • DARK HUMOR:  A Lovecraftian glossary of over 300 obscure adjectives and evocative terms, hungrily palpitating for your rugose and squamous delectation.
  • LAVISH QUOTES AND ILLUSTRATIONS:  This volume was made to honor and celebrate the golden age of fantasy and weird fiction, and features many quotes from the masters (Dunsany, Lovecraft, Machen, Poe, Verne, Wells, and so forth).  It also feature dozens of haunting masterworks from artists old and new.
  • And much more!


THE OLDSKULL MONSTER GENERATOR is the latest FRPG offering from Kent David Kelly, the author of over twenty books including the popular Castle Oldskull line of OSR gaming supplements, the acclaimed FRPG history series Hawk & Moor, and the Lovecraftian epic Necronomicon:  The Cthulhu Revelations.

(V2.00, 100,800 words, 410+ pages.)

From Wonderland Imprints – Only the Finest Works of Fantasy.


To view the entire library of available titles for Castle Oldskull, Hawk & Moor, Old School Essentials compatible supplements, and more, please visit Kent David Kelly's Wonderland Imprints publisher page.

The Wonderland Imprints Swords & Sorcery Library


Supplement Title

Primary Game Topics


The Classic Dungeon Design Guide I

Dungeons / Lore / Random Tables


The Classic Dungeon Design Guide II

Dungeons / Lore / Random Tables


The Classic Dungeon Design Guide III

Dungeons / Lore / Random Tables


Oldskull Dungeon Generator

Dungeons / Solo Gaming Tools


The Book of Dungeon Traps

Dungeons / Random Tables


Oldskull Dungeon Tools

Generators / Solo Gaming Tools


Game World Generator – Deluxe Edition

Game World / Random Tables


Oldskull Adventure Generator

Game World / Random Tables


Chaotic Descriptor Table

Generators / Random Tables


Dungeon Delver Enhancer

Characters / Lore / Random Tables


Oldskull Warriors

Characters / Classes / Lore


Oldskull Knights

Characters / Classes / Lore


Oldskull Anti-Paladins

Characters / Classes / Lore


Oldskull Plague Doctors

Characters / Classes / Lore


Oldskull Gonneslingers

Characters / Classes / Lore



Characters / Races


Oldskull Half-Ogres

Characters / Races


Oldskull D100 NPC Generator

Characters / Generators


Character Tables

Gameplay / Tabletop Reference


Combat Tables

Gameplay / Tabletop Reference


Dungeon Monsters & Treasures Level 1

Monsters / Treasure


Oldskull Dungeon Encounters

Lore / Monsters / Treasure


Oldskull Dungeon Bestiary

Monsters / Random Tables


Oldskull Dragons

Monsters / Treasure


Oldskull Trolls

Lore / Monsters / Races


Oldskull Monster Generator

Generators / Lore / Monsters


Oldskull Treasure Trove

Random Tables / Treasure


The Oldskull Deck of Strangest Things

Lore / Random Tables / Treasure


City State Encounters

Random Tables / Urban Adventures


The Order of the Scarlet Tabard

Characters / Lore / Random Tables


Captains of the Scarlet Tabard

Characters / Lore


Oldskull Tyrrhenia Map Pack

Game World / Lore / Realm Maps


333 Realms of Entropy

Game World / Lore / Monsters


1,000 Rooms of Chaos

Dungeons / Solo Gaming Tools


1,000 Rooms of Chaos II

Dungeons / Solo Gaming Tools


The Pegana Mythos

Characters / Game World / Lore


The Oldskull Necronomicon

Characters / Game World / Lore


Lords of Oldskull: Krampus

Classes / Lore / Monsters


Character Creation

Basic / Expert (B/X) Characters


1977 Bestiary

Basic / Expert (B/X) Monsters


Adventurer’s Arsenal

Basic / Expert (B/X) Equipment


Turn Tracker

Basic / Expert (B/X) Gameplay


Oldskull Grid War

Basic / Expert (B/X) Gameplay


Hawk & Moor Book I

TSR / Gary Gygax History 1973


Hawk & Moor Book II

TSR / Gary Gygax History 1974


Hawk & Moor Book III

TSR / Gary Gygax History 1975


Hawk & Moor Book IV

TSR / Gary Gygax History 1976


Hawk & Moor Book V

TSR / Gary Gygax History 1977


The Steam Tunnel Incident

TSR History / 1980s


(And more can be found at the Wonderland Imprints publisher page.)

Don't know where to begin?

Each of the Wonderland Imprints series has an acclaimed first introductory volume. You can start there, and then journey further as you choose.

Series include the Black Label Editions (unillustrated tabletop volumes), Castle Oldskull (old school RPG supplements), The Classic Dungeon Design Guides (system neutral dungeon crafting), Hawk & Moor (Dungeons & Dragons history), Old School Essentials (supplements for Gavin Norman's B/X game), Oldskull Innovations (unique experimental products), and the Oldskull Library (classic weird fiction), as well as many Free Supplement Releases.

 Customers Who Bought this Title also Purchased
Reviews (2)
Discussions (7)
Customer avatar
Mark M July 30, 2023 5:49 am UTC
I know its been a while since this has dropped but is there a plan to make a form fillable pdf of the worksheets?
Customer avatar
John D September 27, 2019 1:33 am UTC
I'm also curious if there will be a POD for this awesome book....
Customer avatar
neil S July 08, 2019 10:02 am UTC
When POD
Customer avatar
Kevin M January 22, 2019 1:49 am UTC
Any chance of a P.O.D.? Would love to have a print copy of this to work thru!
Customer avatar
Mason M January 26, 2018 5:57 pm UTC
Holy XXX, KDK. I just bought the Bestiary yesterday, and in my critique I did advise people that there weren't monster statistics or suggestions for powers. I now see why: you'd been waiting to drop this OUTRAGEOUSLY comprehensive monster generator. I'm pretty sure that you covered your bases here.

I'm gonna give a comprehensive review, but at first blush I imagine that this book combined with the Bestiary has obviated the need to pick up another 'monster manual' ever again.
Customer avatar
Frank W January 25, 2018 1:54 pm UTC
How useful is this for Pathfinder? Can I easily convert the generated monsters to Pathfinder rules or is it only useful as inspiration?
Customer avatar
Jean M January 25, 2018 4:23 pm UTC
It's based on SRD5, so you should be able to do so fairly easily.

And besides, the thing's five bucks ... the design worksheets alone are worth that. Even if there wasn't a single number in the whole 400+ pages, just descriptions, it would be worth the price ... think about it, a cup of frou-frou coffee and a donut would cost you more than that. I bought it primarily for the list of descriptive adjectives, and I got my money's worth just from that alone.

It's full of good stuff. It'll be useful.
Customer avatar
Jeffery K January 25, 2018 1:04 pm UTC
I love Castle Oldskull PDFs. I have two complaints and they are minor ones. The table borders are huge black lines that hurt to look upon. The stuff in those tables is awesome. Also, those tables in paragraph form are hard to read.

Again... LOVE THIS STUFF. Don't stop!
Customer avatar
Jean M January 25, 2018 3:52 pm UTC
I have one to add to that: underlined text in blocks, or inside cells in tables, is extremely difficult to read, at least for my aging eyes. The color of the links should be sufficient. Frankly, due to the readability difficulties, I'd rather have the product (all 418 pages of it!) with no links at all, but be able to read it, than have it "convenient" but have to squint a lot. Perhaps a second copy without the underlines, or at least without the links, could be included, much as many products contain screen-optimized and print-optimized PDFs?

But like Jeffrey K said... LOVE THIS STUFF. Don't stop!
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File Last Updated:
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This title was added to our catalog on January 24, 2018.