Hercule Poirot: a retired Belgian police officer & current private detective in England
Monsieur Bouc: former member of the Belgian police force & current director of the railway line
Dr. Constantine: the coroner aboard the Orient Express
Mary Debenham: Daisy Armstrong's governess & instrumental in planning Ratchett's death
Mrs. Hubbard: Linda Arden, famous actress & Daisy Armstrong's grandmother
Colonel Arbuthnot: a close friend of Colonel Armstrong, Daisy's father
Princess Dragomiroff: a Russian princess & Sophie Armstrong's godmother
Hector McQueen: Ratchett's personal secretary & friend of Sophie Armstrong
Mr. Ratchett: Mr. Cassetti, who kidnapped & murdered Daisy Armstrong for money
Countess Andrenyi: Sophie Armstrong's younger sister
Count Andrenyi: the Countess' husband & Sophie's brother-in-law
Cyrus Hardman: a private detective from New York; in love with Daisy's French nurse, who committed suicide
Antonio Foscanelli: the Armstrong family's chauffer
Greta Ohlsson: Swedish; Daisy's nurse; cries a lot
Hildegarde Schmidt: the Princess' maid & the Armstrong's cook
Edward Henry Masterman: Ratchett's valet; recruited by Hardman to help with the murder plot
Pierre Michel: the train's conductor & the French nurse's father