Mr. Mason Dixon is a member of the WESAYSO board of executives presiding over the Sexual Harris hearings in the Dinosaurs episode "What Sexual Harris Meant." The Southern-accented Mr. Dixon has a used car dealer brother and has sexual fantasies involving marmalade.

His name is a reference to the Mason-Dixon line which is used symbolically in the United States as a supposed cultural boundary between what is referred to as the North and the South.