Most of the people saying that he's Fredbear from FNaF 4 and he caused the bite of 83/87 thing which the phone guy mentioned in FNaF 1. However he isn't. Of course in FNaF World that Adventure Fredbear has the same base as Adventure Golden Freddy, but the other Adventure Freddys have the same base too. Take for example: Adventure Freddy and Adventure Withered Freddy, in games both of them have a different design, but in FNaF World they are literally the same, except that Adventure Withered Freddy's color is darker than Adventure Freddy's color, plus that FNaF World is an alternative universe. But what about twisted Freddy's design, he looks like Nightmare Fredbear and Michael possessed Fredbear which became Golden Freddy. Okay first of all, the books aren't connect to the games, and yes some of them can be, but it won't make sense if you put them together. Just like FNaF World, the two books are an alternative universe. And yes Golden Freddy can possibly be Fredbear in the books and the FNaF World, but not in the games. What about the plushies, they look almost the same. The Fredbear plush is most likely a recolor to the Freddy Plush. Let's say that I want to make a Spring Bonnie Plush, the Spring Bonnie plush should be a recolor to the Bonnie Plush except with a purple bow tie. Now let's go to the main point why Fredbear isn't Golden Freddy. Fredbear isn't Golden Freddy because of its design. Fredbear is mostly likely based off Nightmare Fredbear, but wait how come Twisted Freddy looks like Nightmare Fredbear? Ugh not again. One, what I said previously. Two, that's Charlie's point of view, not the Crying child's. Three, Fredbear has a belly color on his lower body and Twisted Freddy doesn't have it. And four, Fredbear doesn't have those green things (I don't know what are those), plus he has five fingers. Ugh okay geez. Now for the design between Fredbear and Golden Freddy. We always know that Golden Freddy is a recolor of Freddy Fazbear, meaning that their base are almost identical, except that Golden Freddy is colored Golden Yellow. For Fredbear itself, he doesn't even resemble to Freddy, even in nightmare form. Sure that the nightmare animatronics are exaggerated and likely a combination of FNaF 1 and FNaF 2 models, but what about Fredbear? I going to explain this. The original four nightmare animatronics are based off the bullies from Night 5 where they scared the crying child and take him to the jaws of Fredbear. Plushtrap is based off the girl who has a spring bonnie doll and mentions that the doll cant let go of her finger, which his behavior is seen in the Fun with Plushtrap. Nightmare Fredbear is most likely to based off the Fredbear who is chubby, wears purple accessories, has a piston jaw, and bit/crush the kid's head. But what about Nightmare? Let's save this guy for later and yes he isn't shadow Freddy or Golden Freddy, but rather the one we see in the shadows. If I was to make a Nightmare Golden Freddy, would it be based off Nightmare Fredbear? Well no, most likely to based off Nightmare Freddy and probably without Freddles. And AGAIN, Golden Freddy is a RECOLOR of Freddy Fazbear.
If he isn't Fredbear, then who is Golden Freddy? Golden Freddy is a ghostly animatronic Golden bear that takes a form of Freddy Fazbear. Golden Freddy was either be possessed by the fifth kid or the crying child which again I'm going to save it for some time. This leaves to FNaF 2 and FNaF 3 where Unwithered Golden Freddy should come from?
I going to talk about FNaF 2 first. Withered Golden Freddy features is unique, but still a recolor of Withered Freddy. However in Night 6, the phone guy said that the spare Golden suit was stolen, most likely either Golden Freddy or Spring Bonnie. It's most likely been stolen by William Afton. Okay I found some pieces that Golden Freddy used to be and here it is. The first piece is the drawing we see in the trailer and the office. The drawing represents Golden Freddy singing to the kids. There is nothing wrong with it, but most likely that Golden Freddy is in free roam mode. The second piece is the give gifts give life minigame. The minigame represents where the puppet gives life to the four kids which became Freddy, Bonnie, Chica, and Foxy. When the puppet gives life to the fourth kid, the fifth kid shows up in the middle and Golden Freddy jumpscares you. The minigame probably takes place before FNaF 2 and may be where Unwithered Golden Freddy comes from. The last piece is the SAVE THEM minigame where if you touch Golden Freddy, then he disappears. Golden Freddy is most likely possessed.
And then there was FNaF 3. Yes this is where the most piece of evidence that Unwithered Golden Freddy comes from. Sure that Unwithered Golden Freddy and his four Unwithered Animatronics comes from the location before FNaF 2, but that's where the five kids starts to give life to each of them. Before that piece of evidence, there is a drawing of Golden Freddy and possibly is Phantom Freddy or the Phantom Bear at the office. Now, the biggest piece of evidence is the Stage01 minigame if you type 395248 at Night 4. Wait a minute, how do you know its a minigame and how it connects to the story. Okay first of all, the Stage01 minigame represents Golden Freddy and Spring Bonnie performing on stage, with three kids. And how do you know what the Stage01 bear is Golden Freddy? The source code shows gfreddy. Who is gfreddy, ghost freddy? No, not even one character who has a g and freddy. Well it has to be Golden Freddy. Supporting that, the minigame is possibly connects to the phone calls from Night 2 to Night 6 from FNaF 3. The phone guy said that there were two suits, one of them is Spring Bonnie (becomes Springtrap with Michael inside) and the other is Spring Freddy, because the phone guy said that the location is Freddy Fazbear's Pizza, not Fredbear's Family Diner. This is where I believed that Golden Freddy used to be Spring Freddy and yes, Spring Freddy is based off Freddy Fazbear, not Fredbear. But why Spring Freddy have 5 fingers and Golden Freddy has 4 fingers? Well the Golden Freddy we see in FNaF 2 and 1 are Ghosts/Hallucinations, while Golden Freddy from Stage01 is a spring lock suit and Unwithered.
If Golden Freddy is a springlock suit, then the drawings in FNaF 2 could be an employee wearing the Golden Freddy and possibly performing to the kids.
Here is the timeline for Golden Freddy existence.
Stage01>Unwithered Location>Pre-FNaF 2>FNaF 2> The suit was stolen by William in Night 6> The ghost of Golden Freddy kills phone guy>Michael sees Golden Freddy in hallucination>Michael painted Golden Freddy purple to dismantle the animatronics>FNaF 3 Phantom Bear/Phantom Freddy>Unknown
It also applies to my story though. This is just a theory, whether it is right or wrong, it's my opinion. If you support it, okay. If you don't support it, then it's your own opinion. We can't confirmed until Scott released the lore, or answers some of the lore. Have a good day people