The Yellow Mythos is a loosely-linked continuity that has come to define the imagined universe revolving around 'The King In Yellow', a fictional, mysterious play in book form, which supposedly can send its readers insane or open a gateway for supernatural events.
The core work is a real book of the same title, The King In Yellow, a late nineteenth century short-story collection by Robert W. Chambers. This features an opening handful of tales in which the bulk of the Mythos' recurring settings, characters, ideas and tone are rooted – plus an equal handful of seemingly unconnected tales.
The sparse seeds sown in those early stories have grown into an enduring yet relatively little-known fictional mythology in the subsequent hundred-plus years, where authors from a variety of backgrounds have pushed the settings and characters into all sorts of interesting and diverse directions. Quiet horror can meet twisted romance, and suspense blur with dark fantasy, as terrible gods from an alien dimension spin their unfathomable schemes via the minds of mortals.
The King In Yellow – the book, the play, and something else entirely...
The actual contents of the play script are almost entirely unrecorded by Robert Chambers' stories, although some of the fiction deals with the fates of those who are ensnared by reading it. Those characters familiar with it largely agree that within it a supreme (though warped) art and truth is undeniably crystallised, yet at the same time it manages to channel an inexplicable horror and madness: to be exposed to its full awful, monstrous and blasphemous corruption is to risk despair, terror, insanity or even death.
This would seem to lie, by some nebulous association, with an ill-understood, unearthly and hideously powerful entity of the same name, the eponymous King in Yellow himself. Without ever definitely manifesting in 'person', his – or its – ominous near-presence nonetheless haunts not only the characters within the play but also the characters in the stories to whom that play is merely a work of art: it is a scarcely comprehensible malevolence, implacable ambition and insidious taint bleeding through from one layer of fiction to another.
A mythology based on hints, fragments and madness
The different tales in The King In Yellow have a number of cross-references but little overtly to do with one another, and only hint at the spectral tragedy contained in the background to events. Just a few tiny fragments of the plot of the play are glimpsed, together with a scant assortment of other clues that may be combed from Chambers' text.
The references his characters actually make to anything in or related to the play are mostly brief, vague and context-free, so these things cannot necessarily be placed in clear relationships with each other. Many, indeed, only crop up amid the ramblings of a damaged and deluded fantasist. Furthermore the same terms may seem to be applied variously to people, places, concepts, objects, or a combination thereof; hence it is sometimes questionable which categories such names even belong in.
The central aspects of the Mythos are notable, in fact, for their nebulousness: concrete knowledge or sane description of happenings is most often elusive to the protagonist characters, and hence equally so to the reader. Chambers sketches his creation so lightly, suggests the nature of events so opaquely, as to require the imagination to fill in almost every detail. The stories that form the canon rely instead on a queasy, shadowy horror and the threat of a barely-understood doom for much of their effect.
This makes for a fictional universe that is wide open to interpretation – consequently it has over the years since been used, borrowed and played with by multifarious authors in greatly diverging fashion. The nature of the setting varies, depending on story and writer, and upon whether a given fiction is concerned with the murky world inside the play or with a version of the 'real world' into which the malign influence of the King spreads its tendrils. Even within a single piece the tone can shift through a genre-melting blend of horror, suspense, science-fiction and even romance. The fact that most of the core concepts are barely hinted at in the original narratives, though, allows for almost limitless bending of the base ideas into new shapes of an author's choosing.
Common interpretations and motifs
Common to the bulk of interpretations, however, is that the play is set amid the dying days of a corrupt and decadent dynasty of a distant world, where a masked ball at court sees the disastrous arrival of a Stranger who wears (or is) the 'Pallid Mask', probably an emissary or avatar of the King in Yellow.
Other frequently occurring motifs include the peculiar, compelling Yellow Sign, the Hyades star cluster in the constellation of Taurus, and the ancient, other-worldly dread city of Carcosa under its "black stars", where "the shadows of men's thoughts lengthen" as its "twin suns sink into the lake of Hali" where the cloud-waves roll...
Where did the Mythos come from?
His stories were heavily influenced by his years as an art student in Paris, and are frequently characterised by the presence of artists, aesthetes and those generally of emotional and susceptible states of mind, into which the worm of the play's malice can burrow. In those uncertain days of the 1880s and '90s, the 'fin de siècle' movement was particularly associated with some Parisian artistic circles; this air of both the closing and onset of an era, the twin excitement and despair anticipating the impending changes of a new century, where degeneration and decadence are as likely as great deeds, filtered through into his writing.
Notably, the colour yellow was strongly associated with (fading) decadence at this point. This can create a dissociation in the mind of the modern reader, who might expect it to mean sunshine and hope, but it is its alternative connotations of sickness and decay that are at play here: as alluded to in the previous section, this mood is commonly evoked when piecing together the setting of the apocryphal play. Meanwhile, the spirit of late 19th-century fin de siècle, its cultural boredom, cynicism and pessimism, is also encapsulated in The King In Yellow's first (and perhaps most essential) story The Repairer of Reputations – especially in its narrator-protagonist Hildred Castaigne but also in its deadpan vision of the then-future 1920s in America.
...and how has it developed?
Many other writers have since drawn inspiration from Chambers in turn, notably famed 'cosmic horror' author H.P. Lovecraft – who adopted a similar style in his writing of only darkly hinting at the ancient eldritch entities or alien gods lurking in the depths of reality, and who borrowed a selection of names to drop into his own tales as well. These included Hastur, a name that crops up in various contexts (or none) in multiple stories in The King In Yellow and came initially from Ambrose Bierce. Such borrowing has ultimately spawned the Hastur Mythos, which bolts the 'Yellow' elements onto the Cthulhu Mythos derived from Lovecraft's works by making the King into an avatar of this Hastur, therein one of the godlike abominations known as Great Old Ones.
Some writers and readers prefer this version of the continuity, while others choose to ignore it and concentrate on those aspects of the mythology native to Chambers' (and perhaps Bierce's) writings: what might be called the Carcosa Mythos. Further authors again may pick and choose aspects from both to create their own personal take on the Yellow universe, expanding it in a multitude of directions.
As noted above, some choose to focus on the mysterious play itself, some on the lives of people who fall prey to it, some on more tenuously related facets still. While some prefer to set fiction contemporaneously with the original stories, some like to bring it into the modern day, and others might send it into the future, possibly by emphasising the sci-fi elements of the mythos suggested by The Repairer of Reputations' use of an alternate future or the mentions of the Hyades and the star Aldebaran, and so on.
The possibilities are legion.
Finding out about the Mythos
If you are not familiar with the Mythos, it is recommended that you visit this wiki's page on The King In Yellow (disambiguation) in order to clarify the various things that the titular term can refer to – book, play, character etc. – in reality and fiction. For example, the fictional play does not actually exist (although there have been reconstructions inspired by the hints dropped by Chambers), but in entries on this site it and things associated with it may be described as if they are real. By paying a little attention to what is being discussed, it should be quite easy to discern what is real and what is fiction – in particular, if in doubt, check the Category tags at the bottom of the page.
The Mythos is not a cohesive entity: although many themes recur frequently and all the stories are inspired to some extent by Chambers' work, they often disagree upon the details. Although not all, many of the stories overlap with the wider Cthulhu Mythos – as implied previously, there is some disagreement about whether this link is a good thing or not! See also Mythos (Definition).
A reader new to the Mythos should sample Chambers' book to gain an insight into where it all (primarily) began – but, even if his writing is not for you, that is not a reason to give up on the entire Mythos if the hints in it appeal since there are many other stories, of many different types, to explore.
The stories of Bierce and Chambers can be found in several formats, the best and cheapest option (in the UK at least) being the editions released by Wordsworth Editions and available from good bookshops or from Amazon.co.uk for £2.99 or less; the same edition of The King In Yellow can be found in the US via Amazon.com for $4.99. As its age means it is out of copyright, the book's full contents can also be found in several places online.
For further reading, The Hastur Cycle has some key stories (although it also wanders into largely-unrelated territory for half the volume) and Rehearsals for Oblivion (Act I) and A Terrible Thing have a fine variety of stories and poems related to the Mythos. These are available from Amazon, although the first is only available second-hand. In addition, the Yellow Leaves series of broadsides collects poetry. The year 2012 saw the release of a brand-new collection of Yellow Mythos stories in the shape of A Season In Carcosa.
Much of the Hastur Mythos version of the continuity is founded upon the scenarios set down for various role-playing games based in a universe where Hastur is a mighty entity, almost a personification of entropy, which has an aspect or persona as the King in Yellow; the wiki pages associated with these games have more information on this mythology.
For more information on the Mythos, a good place to start is the pages listed under the Lexicon category below, which detail a few key concepts.
See also Truth and the Mythos.