Gramma Stuffum is a recurring antagonist of Codename: Kids Next Door. She is a fat old lady obsessed with force-feeding her disgusting food to children to fatten them up, believing that a child that is too fat to move can't get into trouble. She speaks with a German accent.
She was voiced by Grey Delisle.
She first appeared in Operation: N.O.-P.O.W.U.H., in which she was interviewed by The Delightful Children From Down The Lane, who wanted to find a villain to bring havoc upon the KND. They convinced her to do so by saying their foes were famished. Gramma Stuffum then attacks Sector V Treehouse with her food army while their power is out. She is able to fatten Numbuh 1, Numbuh 3, Numbuh 4 and Numbuh 5 into a state of helplessness, but Numbuh 2, who has an enormous appetite and is more tolerant of her disgusting dishes, proves much more difficult to subdue. When he is finally full and about to give up, the Hamsters return and eat the rest of her food. Numbuh 2 then fires Gramma Stuffum back to the Delightful Mansion From Down The Lane, where she decides to feed the Delightful Children.
She appeared again in Operation: F.O.O.D.F.I.T.E., She is apparently revealed to be a cafeteria chef at Gallagher Elementary. During lunch period, the members of Sector V have an extended battle with her and her food, which is implied to be a regular occurrence during lunchtime. Gramma Stuffum then summons the monstrous Slamwich, which overwhelms the children until the super-powered hamster Joaquin appears and eats it. During the battle sequences are lyrically altered versions of the GWAR songs "The Private Pain of Techno Destructo" and "Gor-Gor". GWAR provided the music for this episode under the name "RAWG". After her defeat, she tells them to prepare for lunch the next day and Numbuh 4 throws a chicken leg at her, hitting her in the head as he tells her to get a real cookbook.
- Gramma Stuffum is one of the few villains to win at the end of the episode since her debut alongside Count Spankulot in the series.