Cthulhu
From Jenny Everywhere Wiki
Cthulhu was a fictional eldritch being with an octopus for a head. As they 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)
Behind the scenes
The character of Cthulhu, created by H.P. Lovecraft, is himself in the public domain.