Markiplier is a YouTuber famous for his "Let's Play" videos where he plays a video game while delivering live commentary. He has made "Let's Play" videos for all five of the Henry Stickmin games, just like his co-YouTuber Jacksepticeye.
As a tribute to his Henry Stickmin videos, Markiplier has been given a cameo appearance in Fleeing the Complex. He appears during the Convict Allies route, in one of the final fail screens. When Henry and Ellie choose the truck as their means of escape in the last choice screen, Markiplier can be seen among the other inmates that are boarding the truck.