William Afton

William Afton is the main,later secondary antagonist of the Five Nights at Freddy's series,Cameo Character in FNAF 2 and 4,Bigger Bad of Sister Location,Secondary Antagonist of Pizzeria Simulator, He has also been known as the Purple Guy,   and the Murderer.

He is the confirmed killer of 11 children. His story is told through 8-bit-styled minigames in Five Nights at Freddy's 2, Five Nights at Freddy's 3, a cameo in Five Nights at Freddy's 4 as well as hints through Sister Location,The Presumed Protagonist of Ultimate Custom Night and Non Canon Spin Off,Into Madness.posthumous antagonist in Five Nights At Freddy's 8: Endless Tycoon and FNAF 9.

Five Nights at Freddy's 2
The Purple Guy is a mysterious purple figure in the Five Nights series. First, he is the confirmed killer of 11 children. In the TAKE CAKE minigame, he killed Charlotte outside of the restaurant.

Finally, he lured 5 children into the backroom using cake and a yellow suit. Then the Puppet stuffed them in Freddy, Chica, Bonnie, Foxy, and Golden Freddy suits to save their souls.

Five Nights at Freddy's 4
William appears in a cameo in the fourth game, set in 1983, putting someone in the Spring Bonnie costume in the back room.

SAVETHEM
In the second game, set in 1987, he is implied to have been the nightguard before Jeremy Fitzgerald. He went to murder 5 more kids and messed up the 'Toy' Animatronics facial recognition software, which made them hostile to the employees of Freddy Fazbear's Pizza.

Sister Location
He returns in the fifth game, but under the name William Afton. In the opening scene of Sister Location an entrepreneur is asking him questions about the new animatronics. They inquire why certain features were added and express their concerns, but he avoids answering the specific features they refer to.

He is also the creator of the animatronics and the former owner of the Circus Baby's Entertainment and Rental and, by extension, Circus Baby's Pizza World. William instructs Michael to go to the underground facilities and find his sister. This implies that William Afton is aware of the souls of the children staying behind, and knows his daughter's soul is within Circus Baby.

Five Nights at Freddy's 3
He returns in the third game, dismantling the classic animatronics one by one when they cannot enter the saferoom he is hiding in. However this unleashes the spirits of his victims who chase him in the Safe Room, and William puts on the Spring Bonnie suit, thinking that this will protect him. The locks come loose and kill him, turning him into Springtrap.

Freddy Fazbear's Pizzeria Simulator
As well as being present as Scraptrap, William Afton appears in the Minigame Fruity Maze, wearing the original Spring Bonnie suit, and luring a girl away, with a promise to show her that her dog is alive. He is also referenced by Henry as his "old friend" who started the restaurant chain.

Trivia
His actual motivation for killing the children is still a mystery, although many people assume he did for his own enjoyment, or as part of an experiment to create life from the dead.
 * Freddy Fazbear’s Pizzeria Simulator implies the latter, as a blueprint reveals the Scooper’s purpose; to transfer remnant, a substance that gives a soul its ability to remain after death, into the animatronics.
 * Furthermore, a minigame accessed during the Midnight Motorist arcade game features a man depicted by a yellow sprite, who is shown to be abusive to his son. The "yellow man" is speculated by many to be William's father, and Michael and Elizabeth's paternal grandfather, causing many to believe that William's child murders stem from his own abusive childhood at the hands of his father.
 * He is the main antagonist of the series.
 * He is the Presumed Villain Protagonist of Ultimate Custom Night.
 * His Is Similar to Pennywise ,Jeff the Killer,and Freddy Krueger