|Occupation||Drug dealer and self-proclaimed scientist|
|Relatives||Johnny Test (brother) Susan Test (twin sister) Hugh Test (father) Lila Test (mother)|
|Introduced in||The Great Meatloaf-Off|
|Latest appearance||Shreqical Girl|
|Voiced by||Ashleigh Ball|
Mary is a geek who does experimenting with her sister in the garage. They call it "the lab". They often force Johnny to join in.
When not making potions and shots to shove up Johnny's ass to turn him into a hairy creature they're making meth and rape drugs to kidnap Gil and use on Bling-Bling Bitch so that he is unconsious and they will feed him to the monkeys.
Mary is known for the following things:
-Breaking into Gil's house 4 times
-Sacrificing 3 of her cousins to the fire
-Blowing up one of Little King John's potato knishes with firecrackers and meth
-Shoving meth up Johnny's ass
- Will Smith Fish was revealed to be stalking her, and he may still be stalking her as a ghost after he was killed. After overhearing him rap outside her window one night even though he was already dead, Mary started working with Dan Akyroyd to develop anti-paranormal weapons so she could send his creepy ass fish soul to Hell.