| Term | Definition |
| James Adams | Teenager. Respected agent at CHERUB, has a girlfriend but sometimes cheats, also... (!!!) ... Been on several important missions and has a navy T-shirt. |
| Lauren Adams | Preteen. Younger sister of James. Passed basic training at CHERUB after two attempts, has since then been on important missions and has met great success. |
| Kerry Chang | James Adams' girlfriend; the two met during basic training. Is a great martial artist and speaks multiple languages. Feels pressure to be the best. Has been on many long-term missions. |
| Kyle Blueman | Recruited James, best friends with him. Is known to be neat and experienced. A senior agent at CHERUB; however, often gets in trouble. Has been on numerous missions but these have been accomplished with mixed results. Is also (!!!) which James finds difficult to accept. |
| Bruce Norris | One of James' closest friends. Is a highly skilled martial artist, acts tough; however, he often sleeps with a teddy bear. Often breaks rules as well and faces punishments. |
| Dr. McAfferty | Chairman of CHERUB. Often known as Mac, on a good day. Does not tolerate misbehavior or any breach in the secrecy of CHERUB. |
| Amy Collins | James' swimming instructor in The Recruit. Later leaves CHERUB and moves to Australia with her brother. |
| Shakeel Dajani | Born in Egypt, underwent basic training with James. |
| Nicole Eddison | First started basic training with James, but dropped out on Day 1. Expelled from CHERUB after using cocaine in The Dealer. |
| Dave Moss | The "Cool Guy" on CHERUB campus, he is a skilled martial artist and excels in every assigned mission. Is James' partner in Maximum Security. |
| Gabrielle O'Brien | Born in Jamaica, she attended basic training with James. Is sometimes targeted racially. |
| Bethany Parker | Lauren's best friend; attends basic training with her. Does not get along well with James. |
| Connor Reilly | Is a twin. Passed basic training with James. |
| Callum Reilly | Is a twin. Attended basic training with James, but only passed on the second attempt. |
| Zara Asker | One of the mission controllers at CHERUB. Wife of Ewart. Has 2 children. Is respected and known to be a motherly figure. |
| Ewart Asker | One of the mission controllers at CHERUB. Husband of Zara. 2 children. Known to be tough and "psycho". |
| Mr. Large | The head basic training instructor at CHERUB. Is known to be sadistic and enjoys making his trainees suffer. Develops a grudge against Lauren after she hits him with a shovel. |
| Meryl Spencer | A former sprinter and athletics coach at CHERUB. Is James' handler. |
| John Jones | Worked with M15 before becoming a CHERUB mission controller after The Dealer. |
| Brian Evans | Part of the environmental terrorist group Help Earth. Uses weapons such as anthrax to carry out his plans. Escaped government tracking several times. Targeted in The Recruit and in Divine Madness. |
| Fire and World Dunn | Two young men who were also part of Help Earth and participated in the anthrax attack. |
| Keith Moore | Ringleader of KMG, the largest European cocaine dealer. Runs business with help of juvenile deliverers. Targeted in The Dealer. |
| Junior Moore | Son of Keith. A drug addict and delinquent. |
| Jane Oxford | A wanted weapons dealer who supplies weapons and info. to terrorists and third-world nations. Is wanted by the FBI. Targeted in Maximum Security. |
| Curtis Oxford | Son of Jane Oxford, serving life in prison at Arizona Max for murder; is targeted by CHERUB as a part of the plan to capture Jane Oxford. |