Martin is just like any other 16-year-old, and has a wild passion for the paranormal. But after unwillingly solving an amazing 'out of this world' mystery, he finds himself working as a paranormal Investigator for "The Center". Whether at school or on a mission, he always remains the same outrageous immature teen, constantly bursting with energy. He seldom thinks before he leaps into danger, often to help someone in peril. Martin has a peculiar love for everything slimy, sloppy and gooey - things that make Diana gag. Martin loves to play pranks and creep out his stepsister, who often retaliates with physical or verbal abuse. As the leader of the trio, Martin is also the only one who wears a U-Watch. Voiced by Sam Vincent.
Jenni is Martin's unrequited love interest, she views Martin as immature based on the pranks he pulls on Diana and other students and calls him a "Freak" and most of the time a "Loser". But there are sometimes where Jenni seems interested in Martin because he acts like a gentleman but has no memory of most of it her memory was erased because of the fact it has paranormal ties to it. Or Martin usually does something immature. Jenni is not seen for a semester at Torrington because she moves but it is not clearly stated.
A girl who very similar to Martin and seems to be interested in everything he likes. She likes the paranormal, monster movies, and comic books just like Martin, She was Martin's girlfriend for a brief amount of time before she dumps him because he missed a date with her because he was fighting a Genie that was driven by revenge.
Alex (Totally Spies)
He meets the "Totally Spies" in an episode called "Totally Mystery Much," investagating in the same case (Unfortunately Diana and Java weren't involved in the episode), and had a crush on Clover (One of the 3 spies; Alex, Clover, and Sam) at first. The spies were obligated by Jerry (Their boss that works at an organization similar to The Center but called WOOHP, World organization of human protection) to team up with Martin to solve the case. He believes that Sam is like his sister Diana, he refers to both of them as "buzzkills." In the end of the episode, Alex and Martin end up liking each other because they both have common interests in video games. Unfortunately Martin was called in by The Center to work on another paranormal case. In the upcoming season 6 of Totally Spies, there is a possible chance the characters will cross over, this time probably with Diana, Java, and Billy (It is not yet confirmed, but there is a highly possible chance).
Gerlad Mystery is Martin's father and Diana's stepfather. He is a rational and logical scientist who spends most of his time in the scientific field. Unlike his son he considers anything related to the paranormal "Balderdash." But in season 3 episode episode "Wrath of the Torrington Worm" he finds out about the center and is sworn to secrecy.
Diana Lombard is Martin's stepsister and usually the person who is the target of most of his pranks. She is serious, rational, and a Straight a student the exact opposite of her step brother. Unlike Martin every time on a mission she tries to rationalize everything stating that it is local even the things that are straight up paranormal. Diana has the hardest time keeping her cool around Martin when he makes fun of her causing her to slap, punch, kick or strike him. She is works at the center with Martin and is part of their team.