Hmmmmmm

it's actually a charather from one of the books.

Hmmmm. But it's in the game.

but it originates from the books.

Kinda like the Twisted animatronics?

yeah.

Ngl I wish the Twisted animatronics had a spotlight in one of the FNAF games, like FNAF 4 for instance.

duh! its the Mimic ball from Fnaf world!

In fact, it's the other way around.
Burntrap is actually The Mimic, or one of the Glamrock Endo's infected with the Mimic1 program, that infused itself with Aftons corpse. William is long dead, burning in Ultimate Custom Night for his deeds.
In the Tales From The Pizzaplex books, we see how the Mimic was created ("The Mimic") and how it affected the pizzaplex ("Tiger Rock". "The Storyteller").
We see in the very first epilogue that the Mimic was locked in an underground section of the Pizzaplex when it misunderstood its programming and started killing people. This is why The Mimic runs after Cassie: it thinks she's an endoskeleton and must be destroyed, just like its programming says.

Hope this helps!

Actually it’s both the mimic and William. Burntrap is scrap trapped and probably found the mimics remains and rebuilt his body with it. Then after he was taken by the blob he was probably destroyed.

William died in fnaf 6 imo and Glitchtrap is an AI imitating him

It is William. Using mimic programming maybe.

UCN isn't a canon part of the game and doesn't really afflict the story, although it is rumored the main character you play as is William Afton due to the puppet's death dialogue.

UCN is canon. Some one probs uploaded his conciseness into help wanted *cough cough* Afton cult person *cough cough*

UCN is canon, Scott said so

Hmm

William actually DID die in Pizzeria Sim, evident by UCN, which is Afton’s personal Hell, arranged by Cassidy.
So it’s currently the in the air what Burntrap is. While it does SEEM to be Afton, The Mimic and Burntrap share the same endoskeleton structure.
The Mimic was not made by William, but by Edwin Murray.

FINALLY someone who speaks my language!
I believe, like I said, that The Mimic fused itself with the corpseof Scraptrap/Afton, since we know it can do this as per Epilogue #7 of the Tales From The Pizzaplex books.

UCN isn't a canon part of the franchise though.

actually it is. at least in the sense that it exists.