Leonardo "Lee" Clark is the oldest of his siblings. He is 13 years old in his first debut (14 in season 2) and is considered to the strongest one. He is very athletic and the most powerful spy in the group. His spy suit and his MPCom are red.
Lee's personality is carefree and laid back attitude. He is shown that he does not like homework or schoolwork and is not the best student of getting good grades. Despite of him being a slacker to schoolwork it is shown he loves and haves a passion for sports and also shown he is a talented atheletic (jock) which makes him very popular in school. He plays basketball and football at school and he loves to do weight lifting and rock climbing. He also has a habit of going crazy over girls, which is similar to Clover's boy craziness. He is the oldest of his siblings but usually he acts more like a kid than being the mature one in his family. Lee enjoys teasing his younger siblings, sometimes to the point where they get mad at him, but deep down he really cares much about them and at times he will comfort them and cheer them up when they are down; he is also very protective of his younger siblings and will do anything to protect them from harm. Though in some cases there is times he can be mature like-parent to his siblings.
In his normal appearance, Lee has auburn colored hair that seems to be in the style of a flat top. He has pale blue (and sometimes grey) eyes, wears a red short sleeved shirt with a white "W" on it, burgundy colored pants, red shoes and a red and white wrist band.
Lee being the strongest one in his sibling trio can carry heavy things that his siblings can't carry. He always flies the jet and usually controls it when with one team member or with all his siblings, usually Marc or Megan take control of the jet. He is skilled in spy acrobatics like his siblings as well.
Lee has claustrophobia, which means he can't stand small spaces and reacts to the point he gets really sweaty and causes him not to focus on the mission.