Arthur Ketch

Arthur Ketch is a member of the British Men of Letters.

Overview
Arthur Ketch is first mentioned while Lady Toni Bevell is torturing Sam for information. When all their methods prove fruitless, Ms. Watt suggests bringing in Ketch; however, Toni is vehemently against it.

He is also shown in a flashback killing a vampire, identifiable by the tattoo on his hand.

Later on, Mick Davies retrieves Toni and informs her that he has sent for Mr. Ketch, who is shown preparing to leave the UK. This leaves Toni visibly uncomfortable.

In American Nightmare, Mr. Ketch drives up to the Impala on a motorcycle (first seen in the previous episode) and stares it at for a moment before driving away. He later tracks down and kills Magda Peterson, telling someone on the phone that he cleaned up the Winchesters mess and they were right about the Winchesters being unable to kill Magda.

In LOTUS, Arthur rescues the Winchesters and Castiel from the Secret Service and orders Castiel to wipe their memory before introducing himself. That night, Arthur explains that his job is to "strongly encourage" the Winchesters cooperation with the British Men of Letters and was sent by Mick Davies after Sam called him and hung up. Arthur has Castiel confirm that he's not lying and shows them his arsenal of weapons, including a hyperbolic pulse generator capable of exorcising a demon from its vessel. Recognizing its potential, Sam asks to borrow it and for Arthur to trust them. Arthur eventually gives the Winchesters the generator, enabling them to force Lucifer from Jefferson Rooney and send him back to Lucifer's Cage.

Six weeks later, Castiel contacts Arthur and Mick to help him and Mary find Sam and Dean who have been taken prisoner by the Secret Service. The two men are impressed to learn that the brothers had in fact borrowed Arthur's gadget in order to deal with Lucifer himself. They agree to help in hopes that it will earn them the trust of the American hunters, and through their connections, Arthur and Mick locate Sam and Dean near Site 94.

Once the four encounter Sam and Dean, Arthur is unimpressed to learn that they left survivors. Sam insists the people pursuing them were just soldiers doing their job, though Arthur considers it "unprofessional". Sam, Dean and Castiel head to Mary's car while glaring at Arthur suspiciously. Arthur and Mick watch them drive off and share a knowing look at each other. It is later revealed that Arthur went back and killed all those involved in Sam and Dean's imprisonment, including Agent Rick, Agent Camp, the soldiers and the coroner. Mick reports this while noting that cleaning up loose ends is Arthur's job.

In Stuck in the Middle (With You), Mary visits Arthur after stealing the Colt and tells him the story of its theft from Ramiel. Mary is enraged that Arthur sent her after a Prince of Hell which got Wally killed and threatens to destroy the British Men of Letters if something happens to her sons. Arthur apologizes, claiming not to have known that she was going after a Prince of Hell. Arthur and Mary discuss the legend of the Colt as an excited Arthur unwraps it.

In Family Feud, Arthur accompanies Mary Winchester on a rugaru hunt. Arthur tells Mary he is thoroughly impressed with Mary's hunting skills after she kills three rugarus by herself. Arthur later takes Mary to her hotel and tells her she is one of the best hunters he has ever seen. Arthur also says she is an excellent liar. Arthur tells Mary she should forget her sons as they are a weakness to her.

In The Raid, Mary and Arthur take out a vampire nest together and Arthur expresses his dislike for them trying to recruit the Winchester brothers when they have Mary. Arthur later visits Dean at the Men of Letters bunker and sits down for a drink with him. Rather than trying the sales pitch of the other British Men of Letters, Arthur is frank with Dean about his motives, telling Dean that he is a killer and the British Men of Letters offer him the best chance to express his talents. Arthur sees Dean as the same as him and the two decide to take down a vampire nest together. At the nest, Arthur initially arms himself with a gun, but decides to use a machete instead like Dean. The two men find only one vampire hiding in the nest and Arthur beats upon her before Dean stops him to try things his way. When Dean promises to grant the vampire a quick end, she tells them that her nest is going after the British Men of Letters.

Alarmed, Dean and Arthur rush back to the British Men of Letters compound to find that Sam has killed the Alpha Vampire and the surviving vampires have fled. Mick berates Arthur who tells him he was trying to recruit Dean and would've succeeded if Mick's operation hadn't screwed things up. He then takes the rogue hunter Pierce Moncrieff for punishment.

In The British Invasion, Arthur sleeps with Mary following a successful hunt. Mary seems tempted to bond with him further but Arthur seemingly disapproves though he appears intrigued by Mary's attempt to have "the best of both worlds." Arthur is later called back to the British Men of Letters headquarters by Doctor Hess. The two await for Mick to arrive. Mick shows disobedience and Arthur is ordered to kill his former friend. While the two stare down at Mick's body, Arthur appearing to have some remorse or regret for his actions, Hess announces that every single one of the American hunters must be annihilated.

In The Memory Remains, Arthur sends a text to Sam pretending to be Mick, checking in if the brothers are home. Sam replies they are not, allowing Arthur to enter the Bunker with a few subordinates so they can wiretap it and search for The Colt. While scanning Dean's room, Mick comes across a photo of Mary with a 4-years-old Dean. Once the operation is complete, Arthur returns to his own headquarters, taking the photo with him. By the time Sam and Dean return home, Arthur calls to inform them that Mick has been sent back to London so they must report directly to him, even if they mutually don't like it. After the call, Arthur listens to the brothers' conversation through a device and hears Dean insult his motorbike. Arthur stares at the photo he took while listening.

Skills
He is a professional killer. He has murdered any 'leftovers' from the Winchester's work without any difficulty. He even cleans up all evidences of these killings or supernatural events. He is also a very capable torturer. He is quite confident about his abilities, as when he and Dean went after a Vampire nest, he instead choose to use a knife instead, because he considered using the Vampire Irradiation Gun as far less challenging.

Equipment
As a member of the British Men of Letters, he has access to its vast weaponry. The engineers of the British Men of Letters have spent years blending sorcery and technology to produce an advanced arsenal to combat supernatural threats.
 * Vampire Radiation gun.pngre Irradiation Gun: The British Men of Letters don't always have to cut off the heads of vampires to eliminate them as they have developed a tool that uses radiation to reorder the DNA of a vampire which turns the vampire's own blood into poison that is lethal to them. It is said to be very effective on large vampire nests.
 * Hyperbolic pulse generator: A device capable to targeting specific angels or demons and exorcising them safely without harming the host. It is capable of removing even an archangel.

Personality
Arthur presents himself as a gentleman of sorts with a strong British accent. He has no qualms about killing people and considers it his job to clean up loose ends. He believes stalking the Winchesters and killing all those they choose to spare as being "professional". He can be a bit of a show off as seen during his formal introduction to Sam and Dean, when he blew up a vehicle belonging to the Secret Service and gladly presented the Winchesters with his vast weaponry. His well-dressed appearance and charming manners clearly hide a much more sinister personality, which Sam, Dean and Castiel are beginning to notice. In a frank conversation with Dean, Arthur calls himself a killer and admits that when he doesn't kill, it bothers him and he works for the British Men of Letters due to their ability to supply him with targets. Arthur sees himself as like Dean in this regard and seems to regard Dean as something of a kindred spirit.

Despite his ruthless personality, Arthur does appear to care somewhat about others. After sleeping with Mary Winchester, Arthur brushed off the idea of them having a relationship, but did so in a way that indicated he had in fact wanted one with her. He also appeared somewhat intrigued by the idea of her having "the best of both worlds" by having both her family and hunting. While Arthur murdered Mick Davies on Doctor Hess' order, the expression on his face afterwards suggests that he had some remorse or regret for having done so.

Appearances

 * Season 12
 * Keep Calm and Carry On (flashback)
 * Mamma Mia
 * American Nightmare
 * LOTUS
 * First Blood
 * Stuck in the Middle (With You)
 * Family Feud
 * The Raid
 * The British Invasion
 * The Memory Remains

Trivia

 * While Ms. Watt implies he's a very proficient torturer, Toni describes him as a psychopath. In return, Arthur calls her "a neurotic, overreaching time bomb" and admits to being her ex-boyfriend and the one person who saw her actions coming. As Arthur is Toni's ex-boyfriend, their dim opinion of each other may come from their former relationship. Indeed while Arthur is shown to be a remorseless killer in general, after killing Mick Davies he appeared to show regret for his actions, indicating he is not totally unfeeling and uncaring.
 * His name is possibly a reference to the famous executioner Jack Ketch, who made a name for himself as the somewhat barbaric executioner of political offenders in the late 1600's.
 * Arthur describes himself as an artist who paints in many colors.