The Letter "M"
Skoolkids 004
Homeworld Earth
Gender Male
Hair Color Brown
Eye Color Brown

The Letter "M" is a skoolchild in Ms. Bitters' class. He sits between Brian and Dib, and is one of the few skoolchildren with a speaking role. 

He seems to agree that Zim is weirder than most of the other kids, but still doesn't think he's an alien like Dib says. He is called "The Letter 'M'" in both the credits and by the other students (or at least by Zita in "Halloween Spectacular of Spooky Doom"), and is never referred to by any other name. It seems to be in reference to his pronounced widow's peak, which gives his hairline an M-like shape. He was voiced by Phil LaMarr.

He makes his first appearance in the comic series in Issue 19, when he's one of the skoolchildren who attend the fake zoo operated by Zim's Roboparents. Seeing the shoddy state of the "zoo" and the fake animals on display, he accuses Zim and his parents of being grifters.