Cthulhu Mythos
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Basic Information

The Cthulhu Mythos is a shared universe created by H.P. Lovecraft and used by many other writers. It forms the basis of the Call of Cthulhu RPG (as well as the Delta Green setting).


Common tropes of the Cthulhu Mythos include:

The Big Bads:

Great Old Ones, Outer Gods, Eldritch Abominations, Titans, whatever you choose to call them, these are the horrific things behind most of the cosmic nastiness…

That list is far from complete - the Mythos is packed full of ancient horrors and alien gods. There's a more extensive list at Interpretatio Cthulhiana - Deities. Some of these are not exactly malevolent as much as incompatible with human life (at least as we know it). Some of them can even be quite generous if approached correctly, except that their generosity may not be all that much fun to receive in the long term.

While human, Abdul Alhazred could certainly be seen as a big bad as well, because his Necronomicon has undermined the sanity of quite a few characters.

Some of the later writers - notably Lumley and Derleth - played up the role of the Elder Gods as a counter force to the Great Old Ones and Outer Gods. This changes the tone of the mythos substantially, removing some of the bleakness and futility that it originally entailed and creating the prospect of something other than tactical victories. This is not entirely popular with mythos purists - who can often be heard to grumble at the sight of investigators waving Elder Signs like vampire hunters with crucifixes, but it does make for a more gamable universe. Elder Gods include:

See Also


The Cthulhu wiki

6. RPG: Trail of Cthulhu has some of the most interesting takes on the outer gods and great old ones.

Game and Story Use

  • As Call of Cthulhu is one of the oldest and influential RPGs out there, it has had an enormous impact on gaming. Elements of the Cthulhu Mythos frequently seep into other settings, especially when Cosmic Horror elements are introduced.
    • Note that the Cthulhu Mythos as a whole was designed to do this - H.P. open sourced it quite early and wove in contributions from his peers who also used his creations in their work, giving a sort of meta-narrative before such things had really been defined as a concept. Later authors have continued the tradition, giving it a degree of verisimilitude that approaches real-world fakelore … and has been mistaken for genuine occultism by all sorts of people, some of whom really should have known better1.
    • By default, CoC tends to be jammed in the 1920s where the original works were set - with occasional excursions to earlier periods. Cthulhu Now, Delta Green and similar works allow play into the modern era (for a given value of "modern" in some cases). The related Pulp Cthulhu is set a decade or so later than the default, and tends to be more two fisted (as befits the pulp genre) with a tommy gun being a practical solution to at least some mythos based shenanigans (as opposed to a source of inappropriate confidence as it is in the original RPG).
  • Charles Stross's Laundry Files and the eponymous RPG based thereon also provide a very modern - and extremely British - take on the Mythos.
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