Captain Hatch/The Devil is the main antagonist of the final season of the BBC three show Being Human and can be considered the overarching antagonist of the series as he's responsible for the Creation of All Supernatural Creatures.
The Devil claimed to have been created by God solely to create destruction, chaos, death and corruption as part of the natural order; and he indicated that ever since Humanity first evolved, he was responsible for influencing them to corrupt them into causing war and destruction among themselves.
It is known that circa 1000 BC or earlier, two Asian Brothers made a pact with the Devil (they would have eternal life, and in exchange they would drink blood), and the Devil then turned them into the first Vampires, and subsequently created the Werewolf and Ghost Curses.
The Devil Tricked
In 1911, the Devil sparked a full-scale war between vampires and werewolves to feed on the energy this created. In 1918, Emil Parsons summoned the Devil to an old castle in France by lying to the Devil that the werewolves and vampires were battling there, and the Devil then came and possessed a French madman present at the castle. Before the Devil could escape upon seeing he had been tricked, Emil, Hal Yorke and Catherine Glass used a Supernatural Trinity blood ritual to bind him to his current vessel Which would enable them to kill him.
However, as it was not a true trinity due to an error on Hal's part, the Devil wasn't destroyed, but merely trapped in the madman's body and unable to reach vampire-werewolf conflict across great distances as he had previously been. The Devil then managed to telekinetically unlock his vessel's harness and escaped while the members of the blood trinity used died.
Trapped in Human Vessel
Sometime in the 1920s, the Devil trapped in mortal form came to the Barry Grand Hotel as an indefinite resident, using the alias Captain Hatch and posing as a retired Army captain. Over the years, Hatch would occasionally use his abilities to force other people at the Hotel to commit suicide, and became bitter and angered over his binding to his current vessel when his vessel's body began to come close to failing and dying. Hatch also claimed that across the years, he suffered from poor sleep and aches due to his vessel's age, and that it was his desire to one day see Hal again and take revenge on him for his binding that brought Hatch to bear this.
In the early 2010s, one day Hal, Thomas Mcnair and Alex Millar came to the Hotel, with Hal and Tom looking for a job. Captain Hatch then saw that if he could manipulate Tom and Hal into fighting, then the conflict between a vampire and werewolf within such close proximity of him could release enough energy to restore him to power. On the same day, when at one point Hatch's assistant Sophie accidentally spilled milk on him, Captain Hatch used his powers to make her write a warning on the wall of Hatch's hotel suite that he would rise, then kill herself by jumping from the suite window. Hatch subsequently partially wiped the warning off the wall before the police arrived. A Day or two later Captain Hatch, while talking with Patsy about Sophie's Death convinced her to hold an employee of the month competition among the Hotel's staff, as part of a plan by Hatch to manipulate Tom and Hal into squabbling and fighting. Later, while Tom was changing Captain Hatch's colostomy bag, Hatch appeared as a sympathetic ear to Tom, manipulating the latter into rebelling against higher-up employees such as Hal by convincing Tom that they regarded people like Hatch and Tom as beneath them. Hatch then visited and manipulated Hal in a similar way, convincing Hal that he was better than the bad luck he'd been getting recently. Hal and Tom subsequently began squabbling and fighting as a result of Captain Hatch's influence and manipulation, and the fighting seemed to Briefly replenish Hatch's power. Captain Hatch also had the Men with Sticks and Ropes force Oliver Fitzwilliam Pryor to trick Alex into coming with the Men to the other side (so that the trinity would be broken and Hal and Tom would be easier to manipulate), and seemed to control the Men with Sticks and Rope as they went after Alex, until Alex defeated the Men by marooning them on the physical plane to die. After Patsy fired Hal and Tom, Captain Hatch used his powers to force the former to rehire them so that Hatch could cause enough further fighting among the two to further restore his power. Hatch then began tormenting Patsy by biokinetically causing her great blood loss, before making her drown herself in the sea outside the Hotel, and Captain Hatch then vowed to himself that he would reduce the earth to ruin upon returning to full power. When a Middle Aged Werewolf named Bobby was brought by Tom to the Barry Grand Hotel as a temporary new employee, Captain Hatch scared and unnerved Bobby. When Dominc Rook came to the Hotel to pick up Bobby before finally deciding that the Department of Domestic Defense weren't needed anymore, Captain Hatch pretended to Rook to be a survivor of a vampire attack who had been saved by the Department in the past. Hatch manipulated Rook into releasing Bobby in his wolf form onto the Hotel during the full moon the following night, by convincing Rook that they had to cause supernatural chaos in order to get his Department reactivated to prevent worse supernatural chaos from erupting; Hatch hoping that the conflict between Hal and Bobby as the former tried to keep Bobby's wolf contained would further replenish Hatch's power. Rook and Captain Hatch played cards in Hatch's hotel suite that night while Bobby's wolf attacked the Hotel, until Hatch sensed Hal, Tom and Alex foil their plot without either werewolves fighting Hal, and thus Hatch did not gain any new energy. Captain Hatch then momentarily lost his composure and convinced Rook that Tom and Hal were a threat to Rook's goal of reinstating his Department. The following morning, Captain Hatch visited Bobby while the latter was alone, and used his powers to force Bobby to hang himself. After Rook had Bobby's body taken away, Hatch watched Alex while she was in Bobby's apartment, in the process giving away to Alex that he was not human and was involved in Bobby's death.
Regaining his Power
Shortly after Bobby's death, Captain Hatch's vessel began to get sicker and closer to failing, forcing him to speed up his and Rook's plans. Rook and Hatch came up with a plan to have Natasha drive a wedge between Tom and Hal, by seducing Tom and secretly feeding Hal her blood, then telling Tom that Hal had forced her to feed him blood. In the meantime, Captain Hatch had to put up with Alex's attempts to prove him to be a supernatural, by pretending to be unable to see her and at one point even allowing her to throw him out of his wheelchair in front of Hal. The following night, when Natasha realised that Tom and Hal weren't truly monsters and tried to back out of the plan, Captain Hatch tricked her into coming close enough to him for him to use his powers to control her. Hatch then forced Natasha to go to Honolulu Heights, and to kill herself there and frame Hal by freeing Hal from his bonds and then slitting her throat with a knife. Shortly afterwards, when Tom began attacking Hal in rage over Natasha's death, Captain Hatch fed on the energy released and his power began to replenish to full capacity. Alex subsequently confronted Hatch in his hotel suite about Sophie, Bobby and Natasha's deaths, and Hatch, having been restored to full power by Hal and Tom's scuffle and thus no longer wheelchair-bound, then told Alex what he was before imprisoning her in her grave.
Enacting the Apocalypse
The following morning, the restored Captain Hatch used his powers to force everyone else in the Barry Grand Hotel to gruesomely kill themselves, then left the Hotel and set about starting the Apocalypse; planning to first wipe out the majority of the British populace by broadcasting his suicide-inducing powers to them, then afterwards dividing the world into four kingdoms each representing one of the biblical Four Horsemen of the Apocalypse (with Europe as the Kingdom of the Dead, Russia and Asia as the Kingdom of Disease, Africa as the Kingdom of Famine and the Americas serving as the Kingdom of War). Hatch first used his abilities to force hundreds of people across Cardiff to kill themselves, before meeting Rook at the Archive. There, Hatch revealed who he really was and forced Rook to give him the emergency broadcast codes, before heading to a TV station and taking control over the crew. Captain Hatch then used the emergency codes to broadcast from the station on all channels to the entire UK, planning to, by doing this, use his powers to force the majority of the nation to kill themselves. Hatch first expressed scorn and admiration across the TV at how humanity had become worse rather than better over the century when Hatch was incapacitated and thus unable to influence and corrupt them, and was then about to use his powers on them when Hal, Tom and Alex arrived. But before the trio could use the same trinity blood ritual used by Hal, Emil and Catherine in 1918 to stop Hatch, the latter sent each of them into a virtual dream reality where they each had or could have the happy human lives that they wanted. Captain Hatch then used his 'multitasking' presence to simultaneously visit Hal, Tom and Alex in each of their respective alternate worlds, and tried to tempt them into staying and living their lives there as humans. However, all three of them refused and seemingly returned to the real world.
Captain Hatch was then about to resume his plan, but just before he could use his abilities on the people of the UK watching him on television, Mr. Rook arrived and attempted to kill Hatch by shooting him; prompting the Devil to flee his madman vessel and possess Rook just before the latter shot and killed the former's previous vessel. The Devil, now possessing Rook as a new vessel, later visited Hal, Tom and Alex at Honolulu Heights. He initially pretended to be Rook, but Hal realized that it was the Devil possessing Rook when he automatically responded to Alex, and the Devil then began unleashing his powers. Hal, Alex and Tom then performed the trinity blood ritual with a true trinity between them, and the Devil then left Rook's body but was kept trapped in the house by the trinity ritual. With no other human vessels in the vicinity, the Devil then re-possessed Rook, and Hal almost immediately staked the possessed Rook; killing the latter and seemingly destroying the Devil forever.
The Fight Goes On
The three wake up and quickly discover that they have become human, with Hal theorizing that with the devil dead, their curses have been destroyed. Happy, the three celebrate their humanity and plan to live normal lives. However, during a conversation with Alex about his dream, Hal mentions that he had told Hatch that his life was incomplete without them and that it would have been better if he had put the three of them together. The scene then changes to show a shelf filled with objects owned by each main character to have lived at Honolulu Heights, before showing the origami werewolf Hatch had made in Tom's dream, suggesting that the three were actually Still Trapped. A Bonus Scene Revealed he sent them into another dream reality where they believed that they defeated and destroyed the Devil and became human. However, after some time, the trinity learned it was another dream reality, and vowed to go to Back to the Real World and Destroy the Devil For Good.