The Serpent

Tahar Rahim plays the role of Charles Sobhraj, the infamous serial killer and conman. Charles Sobhraj is a charismatic and manipulative figure who uses his charm to prey upon unsuspecting tourists in Southeast Asia.

Jenna Coleman portrays Marie-Andrée Leclerc, the girlfriend and accomplice of Charles Sobhraj. Marie-Andrée Leclerc becomes entangled in Charles' criminal activities and must grapple with her own conflicting emotions and loyalty.

Ellie Bamber takes on the role of Angela Knippenberg. Angela is a young newlywed who becomes intrigued by Charles Sobhraj's criminal activities and becomes instrumental in assisting her husband in his investigation.

Billy Howle portrays Herman Knippenberg, Angela's husband. Herman is a junior diplomat who becomes obsessed with exposing Charles Sobhraj's crimes and seeks justice for the victims.

Mathilde Warnier plays Nadine Gires, the sister of one of Charles Sobhraj's victims. Nadine becomes determined to find out the truth about what happened to her sister and seeks justice.

Tim McInnerny portrays Paul Siemons, the Dutch ambassador who initially dismisses Herman Knippenberg's claims but later becomes involved in the investigation.

Dontri Wannarot plays the Santa Cruz Receptionist, a character who encounters Charles Sobhraj during his stay at a hotel in Santa Cruz.