|First Appearance||"Mystery Meat" April 3, 2004|
|Relatives||Jack (spouse), Danny (son), Jazz (daughter)|
|Residence||Fenton Works, Amity Park|
Madeline "Maddie" Fenton is Danny and Jazz's mother. He is a professional jumpsuit-wearing ghost hunter who make it their hobby and goal to study and eradicate "all things ectoplasmic." Maddie is an accomplished ninth-degree martial artist who serves as Jack's partner and equal inventor of Fenton anti-ghost gadgets. She is more down-to-earth than her husband and often supports or keep her husband from getting into trouble or harm. She is often the more sensible of the two. Vlad Masters has been in love with her for twenty years ever since college and has spent time trying to win her heart, developing his obsession for her by programming a Maddie hologram to shower praises on him.
Maddie appears as a non-playable character in Nicktoons Unite!. She was first briefly seen in the background when the heroes first arrive at Amity Park. She was hypnotized and couldn't do anything while he was being held captive by Vlad. She only appeared in the background during the ending of the Amity Park level, and didn't do much.