* Scorpia: A beautiful and mysterious woman who is a master assassin and spy, working for the shadowy organization known as the "Secret Service."
* Alex Rider: A teenage spy for MI6, who is thrust into a dangerous mission involving Scorpia and her connections to a deadly virus.
While Scorpia is the titular character and a major driving force in the plot, Alex Rider is the protagonist of the story, and the book is primarily told from his perspective.
Other notable characters include:
* John Rider: Alex's uncle, who is also a secret agent and is instrumental in recruiting Alex into the world of espionage.
* Jack Starbright: A journalist who becomes entangled in Alex's mission and provides important information.
* Mrs. Jones: Alex's housekeeper and a trusted confidante.
The book explores themes of espionage, betrayal, and the dangers of power, while also delving into the psychological complexities of the characters.