Micheal Afton

Michael is the brother of Elizabeth Afton, C.C (either his little brother or his past self), and FoxyBro (either his older brother or his past self)and son of William Afton.

Michael Afton is theorized as the boy in the Foxy mask in FNaF 4. He and his friends  accidentally killed C.C  while trying to make a prank on his birthday.

Some people believe that he was the Bite's victim.

Michael Afton, as an adult, goes to the pizza place in the game FNaF: Sister Location. On the fifth night, ends up being scooped and having his organs replaced by Ennard. After a few days, Michael vomits Ennard into a sewer, after which we can hear a voice saying "You won't die" several times, and then Michael get up.

Michael Afton wanted to undo his father's mistakes, so he went to work in all the pizza parlors to free the souls of the children killed by William Afton, but the animatronics try to kill Michael, because they think he is William Afton. After the five nights of FNaF 1 and 2, Michael is fired for odor and tampering with the animatronics, which leads we to think that Michael Afton was already dead while working in the pizza parlors in the first two games.

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People believe that Michael had an older brother named Terrence, but this is not canonical. In fact, "Terrence" is a name given to Michael by Fandom.Also, people believe that Ennard and Michael are dating, that Ennard saved Michael from rotting, and that Ennard regretted killing Michael, but  this is a LIE. 

- Ennard and Michael would never date, because Ennard killed Michael, and Ennard is a robot possessed by several children's souls, including Elizabeth, his sister.

- Ennard did not save Michael from rotting, because it is possible to see in the scenes after the custom nights that Michael rotted (he is seen purple in the scenes) and vomits Ennard into the sewer.

- And Ennard obviously did not regret killing Michael.