Sandy Petersen’s Cthulhu Mythos

The Ultimate Guide to the Cthulhu Mythos in Roleplaying

Sandy Petersen’s Cthulhu Mythos is the most comprehensive guide to including Lovecraftian elements in your Roleplaying game, written by the author of the groundbreaking Call of Cthulhu role-playing game, and developed primarily by James Jacobs (creative director of Paizo) and David N. Ross.

This massive tome contains over 100 monster stat blocks, dozens of which are Cthulhu Mythos monsters that have never been described for Pathfinder or Dungeons and Dragons 5e – including new rules for interacting with 25 different Great Old Ones and Outer Gods (they are much more than a simple encounter!).

This is much more than a mere bestiary, however. Inside you will find new rules for Insanity and Dreams; 40 new spells and 30 Rituals – a new magic ruleset; dozens of mythos items and artifacts; dozens of Mythos cults detailed; and four new player races from Lovecraft’s universe – Dreamlands Cats, Mythos Ghouls, Gnorri, and Zoogs – as well as new character options, professions, feats, and race options for them.

5e Fantasy Edition

The 5e Fantasy edition is well over 400 pages long, and was released in late 2018 as a PDF and Summer 2019 as a hardcover. This is not merely a conversion from the Pathfinder edition, but rather a reimagining. It also contains new features, including:

* Over 70 new illustrations not seen in the Pathfinder edition!
* A new avatar of Nyarlathotep, the Dark Demon, as well as more former-human horrors
* Dozens more monsters
* Two new backgrounds (cultist and visionary)
* More Dreamlands denizens
* New character options
* And more!

Enjoy FREE character sheets to help keep track of the action. This beautifully laid out PDF can be printed as often as you like and will be a great enhancement to your friends' Cthulhu-based adventures.

Non-English Editions

Sandy Petersen's Cthulhu Mythos for 5e is now available in German, French, Spanish and Italian. To see more details, please click the links below.

Pathfinder Edition

The Pathfinder edition is a massive 512 pages and was released in 2018. A Pathfinder second edition version is written, and undergoing editing, illustration, and layout. It is expected in 2020.

Dark Eye Edition coming 2019!

Our friends at Ulisses Spiele reached out to us last year requesting to convert the book for their Dark Eye roleplaying game. They are in the process of developing it now, for both their German and English editions!



Shut Up Nerd Podcast


Dice Chukr - Ep. 01 -- Strangers and Rumors
Join our adventurers; Chad, Jacob, Josh, and Seth as DM Travis takes them through the maddening adventure!

Shut Up Nerd Podcast




"I much enjoyed reading and planning to run Dark Worlds: The Ritual. This is my cup of unearthly tea. "

— Andrew Girdwood,

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"...I have rarely received a review item that is so much in my wheelhouse as Ghoul Island. The marriage of the Cthulhu Mythos with my 5E campaign or Pathfinder is like manna from heaven for me. The fact that Sandy Peterson is the person behind this makes it even more appealing."

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A Pawn's Perspective


"Ghoul Island offers a fresh, horrifying adventure that will tax even experienced players, pushing their characters to the brink of insanity...and sometimes over the edge."

— Rob Kalajian

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Board Game Quest


"As a DM I like the excellent plot hooks and flexible options that Ghoul Island offers...I can't wait to have my DnD group play Ghoul Island""

— Brian Winters

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“If you are a fan of horror or interjecting Lovecraftian horrors into your fantasy games, I think that you will really want a copy of Sandy Petersen’s Cthulhu Mythos on your shelves.”

— Christopher Helton

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Talking About Games


“This is one of those books that you will read perhaps 20 pages, and you will feel as if only a couple of minutes passed…Everything is very well written and explained…The illustrations are perfect…notes, by Sandy Petersen himself…A very smooth process to learn how you can implement all of this mythos related information into your Pathfinder roleplaying game….Horror into a high fantasy environment….Overall my highest recommendation for Sandy Petersen’s Cthulhu Mythos. You need to get this book!…A bridge between the Call of Cthulhu Roleplaying game…Lovecraft stories, and the pathfinder roleplaying game…The alien beauty of the cthulhy mythos…dark splendour…dread and insanity…”

— Abraham

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Drive Thru RPG


“Put simply, this book is the best Mythos-themed product for Pathfinder. Period. If you want Cthulhu, or anything related to Cthulhu, this is the book to get.”

— James E.

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“People who are fans of both Cthulhu and Pathfinder will find a lot to love in Sandy Petersen’s Cthulhu Mythos for Pathfinder. Petersen and his team clearly thought through every aspect of the mythos and how it would change in heroic fantasy like Pathfinder. If you’re interested in bringing horror to your Pathfinder game, Sandy Petersen’s Cthulhu Mythos for Pathfinder is well worth the look. It might become your favorite.”

— Beth Rimmels

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Cthulhu Mythos News

The Night is Dark & Young November 20, 2020
Famous Last Words Wanted! November 19, 2020
Night of the Brine November 12, 2020
Mini Offer of the Month November 10, 2020
The Night is Dark & Young October 23, 2020
An Omen in the Stars October 16, 2020
Free Keyless Map Downloads October 13, 2020
Famous Last Words Wanted! October 7, 2020
Mini Offer of the Month October 6, 2020
More Horror with Ghoul Island September 26, 2020
The Pale Shepherd September 17, 2020
Famous Last Words Wanted! September 9, 2020
Ready for Dark Worlds? September 6, 2020
Gaming Practicum Video March 17, 2020
Matt Corley February 26, 2020
Yig Snake Grandaddy February 22, 2020
Yig Snake Grandaddy February 17, 2020
Jonah Bomgaars February 17, 2020
Shout Out to Matt Corley February 5, 2020
More Anatomical Concepts November 10, 2019
More Anatomical Drawings September 19, 2019
Final Opportunity September 9, 2019
Any Anatomy Buffs Out There? September 7, 2019

General Downloads


Dark Worlds Act 3 Keyless Map 3.66 MB 18 downloads

Some folks have asked for the maps in the adventures without the map key to show...

Dark Worlds Act 2 Keyless Map 2.16 MB 39 downloads

Some folks have asked for the maps in the adventures without the map key to show...

Dark Worlds Act 1 Keyless Map 1.41 MB 59 downloads

Some folks have asked for the maps in the adventures without the map key to show...

Yig Snake Granddaddy Gehirs Map 4.45 MB 205 downloads


The Lone Lighthouse 13.21 MB 494 downloads

Dive into the campaign world with a FREE one-shot adventure* (as PDF) that takes...

5E Sagas Character Sheet 3.09 MB 1731 downloads

Enjoy this FREE character sheets to help keep track of the action. This beautifully...

Ghoul Island Act 4 Keyless Map 2.89 MB 172 downloads

Some folks have asked for the maps in the adventures without the map key to show...

Ghoul Island Act 3 Keyless Map 3.65 MB 157 downloads

Some folks have asked for the maps in the adventures without the map key to show...

Ghoul Island Act 2 Keyless Map 2.50 MB 151 downloads

Some folks have asked for the maps in the adventures without the map key to show...

Ghoul Island Act 1 Keyless Map 4.48 MB 214 downloads

Some folks have asked for the maps in the adventures without the map key to show...

Cthulhu Mythos Sagas

Get fresh horror delivered to your doorstep EVERY MONTH!

Sandy Petersen, the mind that created the horror RPG genre, brings the Cthulhu Mythos to heroic adventure campaigns for 5e. The Cthulhu Mythos Sagas are full campaigns, taking your adventurers from level 1 to level 14 or 15. They are standalone but can easily be introduced into any fantasy setting.

Each campaign is published in four hardbound volumes, or acts. They are full color, printed on high quality paper with an elegant spot UV hardcover.

Subscription Service Now Available!

Beginning with Cthulhu Mythos Saga II – Yig Snake Granddaddy – we will offer a monthly subscription to the Cthulhu Mythos Sagas. Each month you’ll get a new act of the campaign, and after act 4, the next month will see the release of act 1 of the next standalone Saga.

Subscription Benefits

  • Beginning November 4, 2020, each book will be priced at $25 and will ship for free.  Initial orders placed prior to November 4 were charged at the old rate of $19.99 + shipping.  Subsequent renewals will charge at the new rate with free shipping.
  • Free PDF of monthly Campaign Act available immediately upon purchase
  • Each title delivered 1 month prior to general retail release
  • 10% Discount on all roleplaying miniatures
  • 10% Discount on all roleplaying products
  • Exclusive subscriber discounts and products offered periodically
  • Your subscription includes FREE Cthulhu Mythos character sheets
  • Month-to-month subscription, cancel at any time

Enter the Dark World after the exciting conclusion of Yig Snake Granddaddy!

The next four sagas in your adventure series is NOW AVAILABLE!

In Dark Worlds, the new Cthulhu Mythos for 5e campaign, You and your friends become unwitting pawns caught up in the blunders of a mad ruler. His insane attempt to curry favor with the dread Fungi from Yuggoth results in your being teleported across space to the nightmare world of Yuggoth. The ritual keeps you alive … for now. But how long will its effects last? Your only hope is to track down the wizard Mustafo who was transported along with you, and who knows the spell of return. Unfortunately, Mustafo has been taken by the Fungi for their dire purposes and your attempt to rescue him have drawn their attention …

75+ full color pages in hardcover of Cosmic Horror!

In Act 2: Nithon, you traverse the Radiation Wastes of Yuggoth, encounter creatures and hazards from nightmare as you seek the Forest and City of Nithon. Here lies the Green Pyramid of the Watcher. The Pyramid awakens before your eyes, and you must explore its fearsome depths. Meanwhile, you are in constant threat of being caught up in the battles raging between the Watcher and its spawn versus the Fungi war-cyborgs.

In Act 3: The Zepzeg Cycle, you are brought to Yuggoth’s moon Thog, where you learn of the existence of the Zepzeg – a spacefaring alien species in many ways the antithesis of the Mi-Go. Plus, you learn of a lost colony of gnorri here so far from your world. Can you reconcile the Zepzeg, the Gnorri, and your own goals? Negotiate with an antediluvian entity of enormous psychic power, assist the Gnorri and the Zepzeg to forge alliances to help you in the difficult strife ahead, and find the awesome grimoire detailing a weapon of unthinkable might.

In the fourth and final Act of Dark Worlds, The Green Pyramid, the time has come at last to take the fight to the dread Mi-Go; the Fungi from Yuggoth. Returning to Yuggoth, you find that the Fungi have not been idle in your absence. Can you overcome the Fungi’s might, even with your new allies and eldritch constructs? An epic sacrifice allows ingress to the Pyramid, and you are ultimately led into the Null dimension and confront a being of mindless destruction. The campaign ends by giving you a choice with repercussions that echo across the galaxy. 

Introducing a new pricing model on all Cthulhu Mythos Sagas subscriptions designed to save you money!

Rather than receiving a flat $5 discount on each book and paying full shipping prices, beginning November 4, 2020l you will pay retail price of $25 for each book but receive free shipping on all subscription orders.

This means you will save a minimum of $6 - $12 on each monthly installment. Your savings will only increase over time as postal rates continue to climb.

Price change takes effect Nov. 4 with the release of Dark Worlds Act 3. Initial orders placed prior to November 4 were charged at the current rate of $19.99 + shipping.  Subsequent renewals will charge at the new rate with free shipping.

Saga IV: The Big Sleep

Coming January 2021!

Saga V ~ Coming May 2021!

Ghoul Island introduces the Cthulhu Mythos to your heroic fantasy campaign as only the mind that created the horror RPG genre can!  Ghoul Island is a full campaign, taking your adventurers from level 1 to level 14.  It will be published in four volumes, each a separate act.

The first act, Voyage to Farzeen, will take PCs from 1st level to 5th.  It begins with a mutiny and ends in the underground tunnels where our adventurers discover an ancient temple dedicated to a horror thought to have been vanquished long ago!  Ghoul Island can easily be introduced into any 5E fantasy campaign and setting!

Get all 4 books for the price of 3 with coupon code CRITICALROLE

Each act is 50+ full color pages in hardcover...

...with new monsters to fight...

...and new locations to explore!

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Ghoul Island - Available Now!

Ghoul Island “Essentials” Miniature Pack

Ghoul Island “Essentials” Miniature Pack


In Yig Snake Granddaddy, the new Cthulhu Mythos for 5e campaign, evil serpent folk seek to bring back prehistoric times, complete with pterodactyls, dinosaurs, and other monstrous beings.

In Land Out of Time, the first act of four, your player characters adventure into the wilds of Yilan, a primeval wilderness infested with carnivorous slime molds, gigantic crocodiles, and other lost horrors. The heroes encounter an evil serpent wizard, who prepares for an evil ritual beyond belief.

Betrayed, marooned, and hunted by super-intelligent enemies, can the heroes even survive, yet alone prevail?

Yig Snake Granddaddy and the Cthulhu Mythos Saga Subscription debuted in May 2020.   Get the full set now with free shipping!

Each act is 75+ full color pages in hardcover...

...with new monsters to fight...

...and new locations to explore!

stop here

Yig Snake Granddaddy - Now Available