You may not recognize me at first, but I assure you, it's still me.
— William Afton
Springtrap (also known as William Afton in the credits and Afton in UCN) is one of the main antagonists and a salvageable animatronics in the game: Freddy Fazbear's Pizzeria Simulator and he holds the corpse and conscience of William Afton (himself).
He will try to attack the player when trying to salvage him, but if the salvage is completed properly, he will try to attack the player from the vents. Sometimes, when he is very close to the office or moving, the player will hear Springtrap speaking to them.
He used parts from other animatronics to repair himself, Springtrap has a very peculiar appearance and is a lot more damaged and withered than in the third installment, but he is still in his trademark rotten greenish-yellow color. He has a drastically different appearance than his counterpart in the third game, because, Springtrap lacks the right part of his forearm, somewhat exposing parts of his bones. He also has large buck teeth on his upper jaw and his lower jaw resembles that of a nightmare animatronic from the fourth game: FNAF: 4.
His head doesn't look even remotely similar to his previous one, but, it's implied that he was attempted to repair himself after the Fazbear's Fright fire, and as some parts appear to be from Freddy, but, it's likely that he used salvaged parts from Fazbear's Fright to fix himself after the fire in a similar fashion to Scrap Baby and Molten Freddy. His left eyeball is partially covered by a cable. Both of his ears are missing large portions of their upper halves. Also, unlike his third game counterpart, His mouth hangs open, and has Freddy Fazbear-like foot coverings, whereas in the third game, he wears a permanent grin, with his mouth closed, and had no fur from the shins down.
Ultimate Custom Night
Afton has the distinction of having the simplest mechanic in the game, but also possibly the scariest. He will only attack once per night, and there will be no way of knowing in advance when this attack will happen, or if it will happen at all. He will always attack from the vent on the right wall, and when he does, there will be a violent clamoring sound in the vent and the lights will flicker. When this happens, you will have only a fraction of a second to close the vent door or your run will end with Afton screaming in your face.
— Scott Cawthon describing Afton's behavior when Ultimate Custom Night was under development
When William Afton is enabled, and he may appear at a random time during the night, but Afton's approach is indicated by a loud clamoring noise and the lights dimming in the office, and you have a short amount of time to close the side vent's door to prevent him from jumpscaring you and ending your night, but, unlike Balloon Boy and JJ who appear in the same entrance, Afton can attack regardless of your monitor is raised or not.
His first death took place in the third installment of the game. When William dismantled the main animatronics at Freddy Fazbear's Pizzeria (long after its closing) he awoke the souls of the five Missing Children who he killed and when the ghosts followed him into the Safe Room, he tried to run away and hide from them in the Spring-Bonnie suit, but when he put it on, he didn't notice the leak from the roof, which caused water to drip onto the suit and loosen the spring-locks, violently killing him and leaving his soul to inhabit the suit years later in FNaF 3, where he became the character known as Springtrap.
Freddy Fazbear's Pizzeria Simulator
His second death took place after he was being lured into a fake restaurant by his old partner, Henry, and the building was set on fire. The spirits of Elizabeth, Michael, Henry’s daughter and the remaining children are permanently freed, but William's spirit was cast into the "Darkest Pit of Hell" as said by Henry, as he explained that the location was all a trap in the True Ending of Freddy Fazbear's Pizzeria Simulator.
The following information contains spoilers. To view them, click the [show] tag.
What a deceptive calling, I knew it was a lie the moment I heard it, obviously, but it was intriguing nonetheless.
— After a successful salvage
That was easier than I thought it would be.
I always come back!
Fascinating, what they have become.
Bittersweet, but fitting.
How can I resist, a promise such as this?
You may not recognize me at first, but I assure you, it's still me.
— William presumably screaming at his son and old business partner from the darkest pit of hell from the Old Man Consequences secret minigame.
The same audio, but decoded.
William's jumpscare sound, this is shared with the rest of the animatronics who attack you.
The noise of William clamoring through the vent before attacking.
William Afton is the killer of most, but, not all, of the dead children in the FNaF Franchise (except Elizabeth Afton, who he indirectly killed by accident behalf of Circus Baby), being responsible for the deaths of the children that would go on to possess the main animatronics in the series.
William Afton's appearance in Pizzeria Simulator appears to resemble Spring Bonnie from the Five Nights at Freddy's 4's minigames.
This is the same name that appears in FNAF 3, however, there's no counterpart name for Springtrap. All we can know is that he's credited (in the credits) as William Afton.
William Afton is the 48th animatronic in Ultimate Custom Night and was programmed when Scott deemed the game "90% complete", the 49th spot is won by Lefty and the 50th spot is won by Phone Guy.
Unlike his counterpart in the third game, Springtrap appears to have a fairly bulbous and clean human skull inside his suit as opposed to a mummified head, which surprisingly has lips and ears made of bone.
Although it's possible that his skin has rotten away, revealing the skull and/or the brain.
William Afton seems to comment on his change in appearance, stating, “You may not recognize me at first, but I assure you, it’s still me.”
Though he may also be talking about becoming Springtrap. This could also be a reference to a common quote in the FNaF Franchise, "It's Me".
A glitch may occur where even if nothing is bought, nor has he been salvaged, Afton may still appear in the restaurant.
William Afton, in his human form, has been suggested to be the player in the Ultimate Custom Night from several voice lines the animatronics give out. Theories suggest that Golden Freddy created a personal hell for the spirits to haunt Afton's soul for the rest of eternity.
One of Afton's kill taunts is "Bittersweet, but fitting...", a shout-out to the WWI poem Dulce et Decorum Est, which describes one of the worst horrors of war — death by chlorine gas.
In Ultimate Custom Night, William reuses his line "I always come back" after his jumpscare. Ironically, his mechanic involves showing up once per night, so he will definitely won't come back.
It is assumed that he was deteriorated after the fire at Fazbear's Fright, but he may just have rotted naturally.
His left arm is missing, leaving just a white spike, likely bone, in its place. It is thought his arm was removed in the fire at Fazbear's Fright or rotted off during William's trip to the establishment.
His body seems to be entirely different from his previous incarnation in FNaF 3, leading some to believe that somebody rebuilt Springtrap, and Afton possessed it, or that he rebuilt it himself after getting burnt at the end of FNaF 3, but this may only be the result of Scott Cawthon changing the appearance of the animatronics to give them a new, unique appearance.
It is believed that William is the playable character in Ultimate Custom Night, having been sent to hell and being forced to face his victims and even himself for eternity.
Due to the severe differences in his body's shape, endoskeleton, and overall design compared to FNaF 3, it's highly likely that he somehow obtained a new suit after the events of Five Nights at Freddy's 3, as the difference between these two incarnations is too great to have been only caused by time itself.
Theories claim that Michael Afton is protagonist of FNaF games 1 to 3 and Freddy Fazbear's Pizzeria Simulator, making this game be Afton's his second encounter with his own son.
William Afton, during the Salvaging part of gameplay.
William Afton, while being salvaged (Neutral).
Ditto, but glancing at the player (Agitated).
Ditto, but he is positioned completely upright (Hostile). Please note the visible teeth.
William Afton's jumpscare during the Salvaging part of gameplay.
A frame from William Afton's salvage jumpscare showing most of his body.
William Afton's old jumpscare during the main gameplay.
William Afton's new jumpscare during the main gameplay.
William Afton's last frame of jumpscare during the main gameplay with background.
Last frame of William Afton's current jumpscare.
Ditto, but his old one.
William Afton burning during the True Ending.
William Afton's secret screen in the alley.
William Afton's secret screen flash in the alley.
William Afton's hand from FFPS seen in the bottom left of Springtrap's FNaF 3 variant's BTS from FNaF's 3rd anniversary.