Mark Fischbach, known as "Markiplier" on YouTube, had played through most, if not all of the Five Night's At Freddy's video games. Mark's video "WARNING: SCARIEST GAME IN YEARS | Five Nights at Freddy's - Part 1" is the first video that pops up when you search "Five Night's at Freddy's" on YouTube. He's given a lot of publicity to FNAF's and has helped them gain fans. Mark has starred in comedy sketches on YouTube, and also a few drama sketches starring known actors/actresses such as Felicia Day, Kate Micucci, and Jeff Lewis. 

Overall, Mark's fanbase of about 7,155,831 on YouTube alone, which grows more and more each hour of the day, would bring much more publicity to the Five Night's at Freddy's movie. Mark would be such a fantastic choice to cast as the security guard in the new movie.