Any nutjob who goes around crawling in ceiling panels and wooden rafters stalking little children. A Dr. Big will occasionally lower himself from his humble abode to play Xbox 360, beat his mother with a GPS, or beat any of his captured children. A Dr. Big may also be obsessed with any number of historical figures to the point of insanity. These figures may include, but are not limited to: T2 (the Halo 3 MLG player), Johnny Holmes (the late porn star with a sizable penis), or any made up characters that really don't make any sense.
Kid 1: Woah, did you hear that noise in the air vents?
Kid 2: Oh no, it's Doctor Big coming to get us!