|“||I could keep these powers...but I already have common sense. So I don't want 'em.||”|
Mandy is one of the three title characters from The Grim Adventures of Billy & Mandy world and is possibly the most feared person from the series. She is a cruel, cynical girl with a dark personality and is often seen as scary, even by her own family. In only three of the eighty episodes of the series did Mandy ever crack a smile. She has a tendency to boss Billy and especially Grim around all the time. Strangely, while in the show Mandy has no nose (and was sometimes made fun of because of it), in FusionFall she does, though her Nano remains nasally deprived.
When Billy steals the player's power to activate the totems to protect the planet from Fuse's clutches, Mandy was the key that helped the player recover those powers. She gave the player the Pillow of Common Sense and told the player to smack Billy with it. Strangely, it worked and it absorbed the player's powers back from Billy. Mandy would have kept the pillow and the powers, but decided she already had enough common sense and gave the player back the powers and also helped the player locate a nearby totem. She also hands out missions for those following Mojo Jojo, foiling some of Mojo's plans for the hero, while aiding herself with others. She is very grumpy and angry most of the time.
- When Mandy heard about Mojo Jojo making a monkey army, she wanted to create her own.