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 Sandy Petersen, the author of the groundbreaking Call of Cthulhu role-playing game, and developed primarily by James Jacobs 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 Dungeons and Dragons 5e or Pathfinder – 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
Now Available!

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!

Act 1, Voyage to Farzeen is live on Kickstarter now! 



Beyond The Veil


[In The Big Sleep] There’s plenty of rich political and spiritual drama for a talented DM to weave into the fabric of an exciting escapade, all while anticipating the inevitable appearance of eldritch horrors.

—Benjamin Page, Go Beyond the Veil


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

Mini Offer of the Month January 11, 2021
Mini Offer of the Month December 15, 2020
Meanwhile in Resante… December 13, 2020
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


The Big Sleep Act 1 Keyless Maps 1.46 MB 18 downloads

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Dark Worlds Act 4 Keyless Map 3.38 MB 25 downloads

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

Dark Worlds Act 3 Keyless Map 3.66 MB 42 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 57 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 84 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 216 downloads


The Lone Lighthouse 13.21 MB 536 downloads

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

5e Sagas Character Sheet 3.09 MB 1991 downloads

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

Ghoul Island Act 4 Keyless Map 2.89 MB 185 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 176 downloads

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