Hardman has been portrayed on screen by various actors, including Colin Blakely and Willem Dafoe.
Hardman is a private detective working for McNeil's Detective Agency in New York. At the time of the murder on the train, he was 41 years old according to his passport. This passport also gave his cover occupation as a travelling salesman for typewriting ribbons. 
Not much is known about Hardman's past before the 1930 Armstrong Kidnapping, except that before the kidnapping, he fell in love with Susanne Michel, the only child of Compagnie Internationale des Wagons-Lits conductor Pierre Michel, and the nursemaid of Colonel John Armstrong and Sonia Armstrong.
After the kidnap and murder of Daisy Armstrong, Susanne Michel was suspected of being involved in the crime. She committed suicide before her name was cleared. The actual perpetrator, a gangster named Cassetti was arrested and put on trial but got off on a technicality because of his wealth and influence. Linda Arden, Daisy's grandmother, gathered a group of interested parties for the purpose of avenging the crime and bringing the criminal to justice. Hardman joined the group and Linda Arden assigned him the task of tracking down Cassetti. Hardman finally found Cassetti who by then had adopted the alias of Samuel Edward Ratchett. Thereafter, other members of the group managed to infiltrate Ratchett's staff. Edward Masterman managed to gain employment as his valet and Hector MacQueen became his secretary.
The Orient Express
After Ratchett's murder, Hardman revealed his true occupation to Poirot. He was chasing a couple of criminals throughout Europe, which ended in Istanbul. He wired his boss, and received instructions to return to New York. Before he could, however, he received a letter from Ratchett, telling asking him to report to Ratchett's suite at the Tokatlian Hotel. Hardman showed this letter to Poirot. At the interview, Ratchett showed Hardman the threatening letters that he had received and suggested that he board the same train to Paris as a bodyguard.
Ratchett had suggested that Hardman take the compartment next to his but he could only get compartment 16, at the end of the coach. Ratchett had asked him to look out for a small dark man with a womanish voice. Ratchett also told him he didn't think it would be the first night, more likely the second or third. With regards to Ratchett engaging Hardman to protect him, how much was true was never confirmed in the book.
When Poirot told Hardman that Ratchett was Cassetti, he said he did not recognise the face as he had been out west during the time of the crime. He also did not know any small dark men connected with the Armstrong case. On the train he had slept in the day and watched at night but nothing happened on the first night. On the second night, he did not observe any strangers pass his compartment.
Murder on the Orient Express (1974)
In the 1974 movie, Hardman is played by Colin Blakely.
Unlike the novel, Hardman is an NYPD policeman, and the Armstrong house was on his beat. In the film he is introduced with the Armstrong Kidnapping scene.
At 3:00am, during the kidnapping, Hardman is making love to Paulette Michel (her name was changed from the novel), the personal maid of Mrs Armstrong, in the garden house of the estate. They hear the engine of Lanfranco Cassetti's vehicle driving away from the house. They turn on the light and run outside, but the car had gone.
Most likely it is Hardman and Paulette who show the NYPD the kidnappers' escape route which was subsequently published as a graphic in the Police Gazette.
Hardman is also mentioned when Bianchi tells Pierre Michel to place Poirot in the No. 16 compartment, which is always vacant, and Pierre tells them that it is taken by Hardman.
He is later introduced for his interview: he is a Pinkerton detective working in the Stamboul branch, and has been posing as a theatrical agent. This is unlike the novel, where he is a detective for McNeil's Detective Agency, and posed as a travelling salesman for typewriting ribbons.
He explains that Ratchett hired him to protect him, but he didn't do a good job. He then gives his card to Poirot, and Poirot gives the card back. Hardman looks at the card; it is not the card he handed Poirot - instead, it is a photograph of Paulette Michel, the French housemaid whom he fell in love with.
Hardman is later seen in Poirot's revelation scene, and Poirot reveals that all of them murdered Ratchett because Ratchett was responsible for kidnapping Daisy Armstrong. Hardman's reason for killing Ratchett was because of Paulette. After the kidnapping, Paulette was falsely accused of complicity in the kidnapping committed suicide by jumping out of bedroom window to escape arrest. Hardman later quit his job at the NYPD because they had pressured Paulette into committing suicide.
Hardman is next seen in the murder scene, where he receives the knife from Beddoes, and plunges the knife into Ratchett's body to avenge Paulette. He is the twelfth person to stab Ratchett. He then hands the knife off to Pierre, who was Paulette's father.
Poirot lets them go because, even though they had committed a sinful act of first-degree murder, they had delivered justice to a man who deserved it.
Agatha Christie's Murder on the Orient Express (2006)
In the 2006 video game adaptation, Hardman is voiced by Nolan North, who also voices Edward Masterman and Dr. Constantine in the game.
According to his passport, his fullname is Cyrus Bethman Harman (same as in the book) and he was born on 19 May 1893 in the U.S. He lives in New York and his occupation is given as a salesman of typewriter ribbons. Later he admits that this is a cover. He has another passport which lists his occupation as a private investigator. He also has a ID card identifying him as am employee of the McNeil Detective Agency. This is the same as in the book.
Hardman is first seen arguing with Antonio Foscarelli about enamelled ceramics and which is more beautiful: Hardman believes that Kütahya tiles are the best made in Turkey, while Foscarelli argues that it is the enamelled tiles from Iznik, which he believes are the oldest and most beautiful of the Ottoman Empire. Hardman thinks that there are samples of Kütahya tiles in the bazaar.
When Mademoiselle Antoinette Marceau arrives, Hardman and Foscarelli ask her to deliver a sample of both ceramics. Marceau brings forth a hand-painted Kütahya bowl, claiming that it is the most beautiful, settling the argument.
Hardman is next seen on the train, talking with Foscarelli and Masterman.
Hardman is later seen in Pierre Michel's compartment, holding a passkey. Marceau confronts him and says that if he does not give the key to her, she will have a couple of the staff take it from him by force. Hardman boastingly says that he'd like to see them try, and Marceau asks if he really would; Hardman gives her the key.
Marceau asks what he was doing searching through Michel's belongings, and he responds with "Your job!"; he knows that she is working for Hercule Poirot. Marceau interviews him and he gives her the information: he's a salesman in typewriter ribbons, heading for New York by way of Paris, and discovered footprints outside the train, believing it to be a man's size 7 shoe print. When asked why he has a blackjack - a leather sack filled with lead shot - in his suitcase, he reveals that he is actually a private investigator working for McNeil Detective Agency in New York City, and that Ratchett called on him to protect him while en route to Paris.
After Ratchett is revealed to be Lanfranco Cassetti - the man responsible for the kidnapping and murder of Daisy Armstrong - Hardman says that he should have recognized him, having seen his name in the newspapers. He also explains that Cassetti made a lot of enemies in the American criminal underworld, often leaving his partners in crime to "face the music" whenever the police were on their trail, and that some assassin may have finally caught up with him.
He explains his movements the previous night: he played cards with Foscarelli, then went back to his own comparment, leaving the door ajar and staying up all night.
Using a ham radio, Marceau learns that Hardman has worked with McNeil since 1919.
During the next interview, Hardman says that he's always loved French girls.
During the final conclusion scene, Hardman admits that he fell in love with Suzanne Ferrier, the housemaid of the Armstrong Family. They were going to get married and ask her uncle and guardian Pierre Michel for approval, but when the kidnapping happened, it was too much for her and caused her suicide.
It is revealed that all of them killed Cassetti as revenge for Daisy's death. Hardman would track down many false leads before he found Cassetti. His work led him from New York to Mexico to Brazil.
Poirot lets the murderers go as they had killed an evil man.
Agatha Christie's Poirot: Murder on the Orient Express (2010)
This character does not appear in the 2010 adaptation.
Murder on the Orient Express (2017)
In the 2017 film, Hardman is played by Willem Dafoe.
Hardman is introduced as an Austrian-German Professor of Engineering named Gerhard Hardman. He is very racist towards other nationalities and skin colors.
After lunch, Hardman complains to the conductor Pierre Michel about being seated with Dr. John Arbuthnot because he is black. Mary Debenham - who is seated nearby, and is in love with Arbuthnot - reprimands him for his racist views. Hardman compares the mixing of white people and black people to the mixing of red and white wine: that it would be "to ruin them both." In response, Debenham pours her red wine into her white wine glass, quipping, "I like a good rosé," before walking off.
Hardman is later interviewed by Poirot, and he explains what his purpose on the train is: he is going to a conference in Turin, Italy, to discuss the military use of bakelite; he is the only Austrian representative who is attending the conference, alongside Italians, Spanish, Swedish, Belgian, African, and Latin representatives. Without Hardman, the talks will be substandard.
He says that he has never travelled to America, and calls it "a cesspool of miscegenation", and their melting pot a "cast-off scraps; the world's dogbucket".
He also compares the different nationalities to farm animals, saying "The Italians are cows; the Spaniards and Swedes, sheep; the Belgians..." Poirot, who is Belgian, turns to him with a condescending look, and Hardman suddenly stays quiet.
In the script, the only thing that Hardman says about the Belgians is that they are not entirely dirilect. He then says that the entire African deligation is suitable towards athletics and labour, but not science. Lastly he says that the Latins are murderers, felons, and thieves.
Hardman is later seen after Poirot is chased out of the Andrenyis' room by a furious Count Andrenyi; Poirot had just identified Countess Andrenyi as Helena Goldenberg: Sonia Armstrong's younger sister. As Poirot exits, Hardman, holding his gun, bashes the door into Count Andrenyi, knocking him out. He tries to convince Poirot that the Andrenyis are the killers, but Poirot dismisses this, and reveals that Hardman is not Austrian or a professor, because when he said "Turin", he put emphasis on the "u" instead of the "i". Hardman reveals that he based the character of Herr Professor Gerhard Hardman off of a Kraut butcher from his New York hometown.
Hardman apologizes for the inapproapriate racial jokes he added to the character, and even says that he is actually half-Jewish. Gerhard Hardman is actually Cyrus Bethman Hardman, a Pinkerton detective working with them since 1904.
Poirot reveals that Hardman is lying about how long he has been a Pinkerton detective as well, revealing him to have previously been a policeman by his gun. Poirot could identify the checkered grip and checkered trigger, the widened rear sight, and the polished blue finish: alterations made to the Colt Army Special for their Official Police Positive model, issued in 1927. Poirot tells Hardman to leave his gun when he walks out.
Hardman is later gathered with the others when Poirot reveals who the killer is. Poirot mentions that Hardman was the police officer who fell in love with Susanne Michel: Pierre Michel's sister. Hardman would later attend her trial - she had been arrested on suspicion of aiding Daisy Armstrong's kidnappers - and witnessed the travesty of justice, when Hector MacQueen's father insisted that she was guilty. She would later take her own life, and Hardman quit his position.
Hardman claimed that Susanne was gentle and fell in love with him. Hardman, who felt old and grey, told her that she could do better at picking a lover, but she had picked the right one, and was always on time for every date.
Poirot reveals that they all committed the murder, under the command of Linda Arden, who was masquerading as Mrs. Caroline Hubbard. Hardman was the first one to stab Ratchett, after placing his hand over Ratchett's mouth to silence him while he became the first person to stab him.
Poirot puts them all to the test: he presents Hardman's police revolver - which he had confiscated - on the table and tells them that if they were to go free, they should kill him as he cannot lie to the police. Arden takes the gun and tries to kill herself but fails; the gun is empty.
Hardman is last seen on the train, sitting in a chair, with a sad expression on his face; Edward Masterman consoles him.
In the novel, Hardman is a big, flamboyant American with a big, fleshy, coarse-featured face, a loud, nasal voice, and an athletic build.
He wears a loud check suit, pink shirt, and flashy tie-pin, and chews gum.
- In the 1974 film, Hardman has dark brown hair in a receding hairline, brown eyes, and big ears.
- He wears a grey Prince of Wales check wool jacket, a grey diamond-patterened Jacquard sweater with red lining, a pink button-down shirt, grey flannel trousers, and brown oxford shoes.
- In the 2006 video game, Hardman looks similarly to the 1974 film.
- He wears a green check suit, a orange jacquard sweater, a pink button-down shirt, a two-tone purple-and-orange tie, grey pants, and brown shoes.
- In the 2017 film, Hardman is in his early 60s, and has greying brown hair and blue eyes.
- He wears brown tortoise shell round reading glasses with non-polarized lenses, a full-belted heavy tweed 3-piece hunting suit (inspired by an early European hunting jacket) with patch pockets and pleats on the back yolk, an olive-green waistcoat, a matching knit tie in a tight Windsor knot, a white club-collar shirt, and dark brown lace-up cap-toe oxford boots.
- In the exterior scenes, he also wears a grey fedora with an olive green band, an olive green wool knee-lenth overcoat, and dark brown leather gloves.
- According to the 2017 film, Hardman is half-Jewish.
- In the 2017 film, Hardman's weapon is the gun he used while he was still in the NYPD: a Colt Police Positive manufactured in 1927. It is technically a Colt Army Special with modifications.
- Poirot was able to identify this gun by looking at its distinguishable features: a checkered grip and checkered trigger, widened rear sight, and a polished blue finish.
- According to Chapter 9 of Part 2 of the novel, Hardman says that his full name is Cyrus Bethmen Hardman.
- Chapter 9 of Part 2