|Also Known As||Nerd (by Lil)|
|Friends||Nerd Posse (group)|
|Voice Actor||(needs research)|
|First Appearance||"Ladies' Man (Ladies' Boy)" (2007)|
|Last Appearance||"Brothers Grimm" (2008)|
Mario is a character who appears in "All Grown Up!" in the episodes "Ladies' Man (Ladies' Boy)" and "TP+KF". He is always seen with a group of nerds who seem to rival Tommy, Chuckie, Phil, Lil, and Dil. In "TP+KF", Mario is approached by Chuckie to see if he can go trick-or-treating with him, he turns down Chuckie's offer as he was going with his nerd friends as a "carbon atom" which has six electrons and there was six people in the group. Mario was also seen in "Bad Blood" to watch the alien autopsy tape at the Pickles residence. Finally, in "Brothers Grimm", Mario is seen talking to a friend about the winner of "Really Talented American Icon". He asks Tommy for his opinion on the winner, only to be told to "jump off a cliff".
Mario is a light darkish-skinned kid with a pointy long nose and brown hair. He wears a white work shirt with a chest pocket that carries his writing utensils. He also wears grey pants and red shoes, bearing resemblance to a prototypical nerd.
- His voice seems to be different in "Ladies' Man (Ladies' Boy)" when comparing it to his voice in "TP+KF".
- He calls Chuckie a "nerd" in "TP+KF" after he suggests for them to go as a nitrogen atom, which has seven electrons.
- He is a part of the "Future Engineers Club" and constantly rivals Tommy's club, the "Audio Visual Club".
- His club, the "Future Engineers Club", has won the best float at Jim Jr. Junior High every year until they lost to the "Audio Visual Club" in "Ladies' Man (Ladies' Boy)".