In some ancient civilizations the Wolf was a symbol of the underworld. In Egypt, the guardian of the dead was Anubis who was a wolf-headed god. The jackal portrayed as black was the symbol of both death and regeneration.
William is also the one who hid inside the suits and kidnapped and killed children, leading to the assumption that William Afton is The Purple Guy of FNaF 2 and 3 (he is killed at the end of the book when Charlie sets off the spring locks in his suit).
Five Nights at Freddy's (often abbreviated to FNaF) is a series based around an indie point-and-click video games centered around jump scares. The series is created, designed, developed, and published by Scott Cawthon for the Microsoft Windows, iOS, and Android platforms, with console versions under development.