Gregory is an animatronic, I'm not crazy let me explain.

When Gregory is captured / killed by an animatronic he looks static, some of you will say that it is for better aesthetics, I say no.

In the trilogy of the fnaf books (The Silver Eyes, Twisted Animatronics and Fourth Closet) Charlie / Charlotte is an animatronic that thanks to the illusory discs seems human, because I think Gregory is like Charlie, which explains how it fits inside Glamrock Freddy and the static when dying.

End of theory, tell me what you think.