Michael Schmidt is the presumably evil twin of Scott and the overarching antagonist of the Joy of Creation series.
It is implied throughout Story Mode that Michael is the reason the Ignited animatronics came to kill Scott's family in the first place as when Scott asks what the killer robots really are in the beginning cutscene of the Basement (Night 4), only Michael replies with "your creations".
In the Ending, he led Scott on by trapping him in the Attic when he told Val that he was going to "help" him get out of the house.