A Reference (or Ref for short) is a character that belongs to an MFGGer. Usually these characters are simple edits or recolors of existing Mario franchise characters, and sometimes even completely original and unique characters. MFGGers with a reference typically display them in their avatar, or as a link(s) in their signature (mostly crediting various people who have drawn them).
Lately, there has been a dramatic increase in the amount of references. More MFGGers have been creating them, and drawing others references as well. There have even been a few threads on the old phpBB forum iteration that consist of drawing a plethora of member's references, such as Friendly Dictator drawing dozens of MFGGers in the style of the TV show Adventure Time. Other members like Mit have created a thread dedicated to drawing MFGGers in a certain style as well.