In the novel Murder on the Orient Express, Dr Constantine is a Greek physician who helped Hercule Poirot by examining Ratchett's dead body and accumulating all the scientific facts. He is described as a small, dark man. On the Orient Express, he travels in the Athens-Paris coach.
Murder on the Orient Express (1974)
In the 1974 film, Dr Constantine is played by George Coulouris. Like in the novel, he assists Poirot in the investigation and examines Ratchett's body. However, in this adaptation he travels in the Pullman.
Murder on the Orient Express (2001)
Agatha Christie's Murder on the Orient Express video game (2006)
In the 2006 video game adaptation, Dr Constantine is voiced by Nolan North.
According to his passport, his full name is Stavros Constantine. This first name does not occur in the original story. His passport does not give his date of birth.
In this adaptation, Dr Constantine joins the train in Belgrade, and travels in the Athens-Paris coach, where he occupies Compartment 13.
Agatha Christie's Poirot: Murder on the Orient Express (2010)
In the 2010 adaptation, Dr Constantine is played by Samuel West. He is a Greek obstetrician who is visiting Ankara and on his way back to the U.S. He is the one who finds the train conductor's button on the floor while he and Poirot are interviewing Mrs Hubbard in her compartment.
Poirot suggests that Dr Constantine was Mrs Armstrong's obstetrician, and had seen the Armstrong family suffer as a result of Daisy's kidnap and murder. This is not mentioned in the novel.
In the reconstruction of the murder during the denouement, Dr Constantine is the ninth person to stab Ratchett, after receiving the knife from Masterman. He then hands the knife to Pierre Michel. This is different from the novel, where Dr Constantine did not take part in the stabbing.