Cthulhu
Cthulhu was a fictional eldritch being with an octopus for a head.
As the two grew up, Will Severn often told stories about Cthulhu to his younger sister Wendy. Upon meeting Jark Haine later in life, Wendy was superficially reminded of Cthulhu. (PROSE: The Grand Multiverse Hotel) Ibdis and Junter were also familiar with Cthulhu, referring to the unspeakable horror as “Cthulhu” (COMIC: Cthulhu Toilet) and “a Cthulhu monster”, respectively, on separate occasions. (COMIC: Junter's Guide to Plumbing)
In one universe, the Cthulhu Kid existed as an outlaw in the Wild West, having traits in common both with the conventional Cthulhu and with the Sundance Kid. (PROSE: Showdown in the End Times)
Behind the scenes
The character of Cthulhu, created by H.P. Lovecraft, is himself in the public domain.