Twelve-year-old Megan is an optimistic, high-energy girl who has been hanging out with her brothers forever. Her relationship with them is typical: anything the boys can do, she thinks she can do better! When the boys tell her that she's "just a girl," she gets mad and becomes even more competitive.
Marc is 12 years old, and the intellectual one in the group. His knowledge of every subject known to humankind is absolutely dazzling, and can sometimes be a little freaky. Marc is also the tinker kid; he loves to fiddle gadgets to change their functions. He would be a perfect spying machine if it were not for a small problem: Marc is a tad immature and totally gullible! He is easy to take advantage of because he's such a nice, naïve, optimistic boy who sees the world through rose-coloured glasses.
As the head of the World Organization of Human Protection (WOOHP), Jerry is a comedic character. He briefs the heroes about their upcoming missions.
Tammy and her family moved from their Beverly Hills mansion to a beautiful penthouse apartment in the Spiez city. But that's not good enough for 13-year-old Tammy who thinks she's slumming it by having to share a building with other people. Ew! Add to that this tragedy: her bedroom (which overlooks the city park) is like a tiny closet. And Tammy's real closet has barely enough room for her personal shopper to hang all of Tammy's clothes! She's one unhappy valley girl.
At thirteen years old, Lee is the grown-up in the pack. While his two brothers share funny, immature traits, Lee is part big brother/part father figure. To him, nothing is more important than Tony and Marc, and he would do anything to protect them.
Eleven-year-old Tony is a hyperactive, no-nonsense go-getter. In his mind, every problem has a simple and very obvious solution. But since he's an impatient tween, Tony has a little too much faith in his common sense and intuition, and doesn't want to waste time "thinking" when he could be out there doing. This impatience creates hilarious situations in his daily life and sometimes lands his friends in big trouble.