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).
Michael Bell (Plastic Man in The Plastic Man Comedy/Adventure Show, voice of various characters in The Smurfs - such as : Grouchy, Handy, and Lazy Smurf, Raziel in the Legacy of Kain video game series, in addition to Prowl, Scrapper, Swoop, and First Aid in Transformers, & Drew Pickles and Chazz Finster in Rugrats)