She wears a dark green shirt with black shorts. Her hair is blonde and styled into high pig-tails. Her most recognizable trait is her dark roots, which would imply that she probably dyes her hair.
Role in Invader Zim
As previously mentioned, she made only three appearances in the show: The first time, Maddy was seen in a pizza advertisement in the episode Bloaty's Pizza Hog; Maddy was sitting down next to Bloaty, eating pizza. In Door to Door, Maddy was a part of the fund-raiser; she chased a fleeing adult with a box of Poop Candy and kicked at his door.
In Gaz, Taster of Pork, it was revealed that Maddy is part of Mr. Elliot's class. She was hit in the head with a turkey and sent hurtling off her chair after Gaz had an outburst of rage (due to a curse inadvertently inflicted by her brother, Dib). When the class cowered in the corner of the room, Maddy could be seen hiding, upside down, behind the students.