Mike Schmidt is the main protagonist in Five Nights at Freddy's. He's the security guard who works the night shift at Freddy Fazbear's Pizzeria. The player plays the game through Mike's perspective.
Not much is known about Mike since the game is played in a first-person perspective and no prior background knowledge was given concerning him. All that can be speculated is that Mike is somewhat fearless, returning to his job for six entire nights before being fired on the seventh (the custom night) for tampering with the animatronics, general unprofessionalism, and odor.
Mike also receives a measly pay for his job, getting only $120 after completion of the fifth night, then a fifty-cent increase for 'over-time' after completing the sixth night. Upon completion of the custom night he will promptly receive a notice saying he is fired.