Cthylla (The Kraken, The Secret One) is an offspring of Cthulhu and Idh-yaa. She is the daughter of Cthulhu, and is critical to his plans, as should Cthulhu somehow die, Cthylla will give birth to him once again. As such, she is guarded by Deep Ones and Yuggya, in what can be assumed to be R'lyeh, as she was at first from the star Xoth, but came to Earth.
Also called “The Secret One” because the cult tries to hide all information about the goddess, most famously by defacing the Columns of Geph. Her legend is dimly recorded in Greek Myth as “Scylla”.
Cthylla is a Great Old One, and is the youngest progeny of Cthulhu and his androgynous mate Idh-yaa. She came from the star Xoth, but now dwells on Earth in Yhe, where she is guarded by Cthulhu's minions. Cthylla is destined to give birth to Great Cthulhu again after he is destroyed in the distant future. She is considered essential for Cthulhu's plans, and is thus vigilantly guarded by countless Yuggya and Deep Ones. In the epilogue of The Transition of Titus Crow, Project X is used in an attempt to kill Cthylla with a subterranean atomic bomb. She is wounded and escapes, but Cthulhu's wrath is a vastly magnified repeat of the events in the short story "The Call of Cthulhu".
Cthylla was not physically described by Lumley, but was featured in Tina L. Jens's short story "In His Daughter's Darkling Womb". Cthylla has the appearance of a gigantic, red-bodied, black-ringed, and six-eyed octopus with small wings. Like her father, she is able to alter her body-proportions at will, such as by enlarging her wings to enable her to fly. While she normally has eight arms like any octopus, she can extrude or retract additional ones at will (she has been known to sport as many as twelve arms). Each arm is equipped with dozens of razor-sharp claws, each about five inches in length.
Jens's short story narrates the capture of Cthylla by researchers who mistakenly believe her to be a rare specimen of a previously undiscovered octopus species. For the sake of preserving and studying the species, they then attempt to impregnate her through artificial self-insemination.
In Peter Rawlik's "In the Hall of the Yellow King" (2011), Cthylla is featured in a more humanoid form or avatar as a possible bride for Hastur.
Cthylla was created by Brian Lumely.
- Cthylla is a character in the fighting game Chaos Code, in the form of a young girl.