1. James Choke: The protagonist of the book. He is a skilled and resourceful teenager who is recruited by a secret British intelligence agency called CHERUB.
2. Lauren Adams: James's best friend and fellow CHERUB recruit. She is brave and intelligent and proves herself to be a valuable asset to the agency.
3. John Jones: The Chief of CHERUB. He is a former agent who is now in charge of training and directing the young recruits.
4. Kerry Chang: A CHERUB instructor who oversees James and Lauren's training. She is strict but fair and helps them develop their skills as agents.
5. Mr. Large: A former SAS officer who teaches the recruits combat and survival techniques. He is tough and demanding but also supportive of his students.
6. Dr. M: The CHERUB medical officer who monitors the recruits' health and well-being. She is caring and compassionate and helps the recruits cope with the challenges of their training.
7. Dana Smith: A CHERUB recruit who arrives at the same time as James and Lauren. She is skilled and confident and quickly proves herself to be a capable agent.
8. Kyle Blueman: Another CHERUB recruit who is initially jealous of James's success. He eventually learns to work with James and becomes a valuable member of the team.