As the multi-tasking director and the head of "The Center", M.O.M. oversees the investigation of paranormal activities throughout the world. Martin's capabilities make him one of her favorite agents - if "favorite" is meant by "the agent that she would rather spend the most time with in the field and out of her office". Also, she is in charge of maintaining peace with Earth and other planets and galaxies.
Her real name is unknown, though she used the alias, Ms. Olivia Mandell (derived from the initials M.O.M.) in the episode "Web of the Spider Creature". It is often hinted throughout the show that M.O.M. might be somewhat of a workaholic by the fact that she was forced to take up a hobby and has never taken a sick day. Her life outside of the Center is also unknown.
M.O.M. is usually a strict, serious, and uncompromising woman who's rarely been known to show her humorous side. One possible source of her anger is how often she is mad at Martin for ruining, blowing up or tampering with her experiments and every piece of gadgetry that she's working on due to his immature behavior and whenever he appears for a debriefing in her office.
Despite her typically dry sense of humor, she is actually quite- as Billy says- "a real party animal." M.O.M is often seen as being harsh and authoritative with her employees, especially Martin Mystery. Nevertheless, M.O.M. is shown to care for her agents and have a strong sense of responsibility.
M.O.M.'s appearance was shown and considered as slender with fair skin, black hair, purple lips, aqua-green eyes and a little black dot on her right upper lip. Her main outfit in every episode is her white scientist lab coat with white pants and white boots.
M.O.M. and Martin are not seen as either close friends or enemies very often. Their relationship usually goes as far as Martin ruining her experiments. However, both hold each other to be valuable members of the Center.
Billy is possibly M.O.M.'s second in command. Billy is usually seen with M.O.M. unless he's greeting Martin or helping Martin with missions.
M.O.M.'s greatest enemy is the creature, Gastromo. He was the first creature that she caught when she was an agent. Gastromo hated her so much that he was willing to mutate her before anyone else.
Role in the series
In the second part of They Came from the Gateway according to the Center's database, before M.O.M came to the Center, she drove an ice cream truck.
Proof is seen by the team in some pictures she accidentally shows them in the episode, The Amazon Vapor, while trying to debrief them on their next mission due to some malfunctions at the Center. When she was an agent, the first creature she captured was Gastromo. It appears her favorite holiday is Christmas when she is always in a rather happy and festive mood and, as Martin says in disbelief, it looks like "M.O.M. is actually having fun."
In the crossover episode of Totally Spies! titled "Totally Mystery Much?", M.O.M. is shown to have a possibly romantic history with the spies' boss Jerry, much to the spies and Martin's displeasure, as she and Jerry spy-flirt between holograms. The initials M.O.M. are said to actually stand for "Mystery Organization Manager", as explained by Martin in that episode.
As of the second part of the final episode, It's Alive, M.O.M.'s evaluation was downgraded for allowing a breech of Center security and for attitude and personality difficulties, she was sent to a training camp to rectify the issues (much to her annoyance). As a result, Billy was left in charge of the Center while she was gone. It is unknown if she returns as the Head of the Center.