Dr. Nicholas Arkham

The Doctor is a 6'1" feet tall (185 cm) adult man of average build. He is dressed in an all yellow and light-brown plague doctor suit, paired with a yellow-striped wide-brimmed black hat and a sharp bird-like white doctor mask as part of the typical plague doctor costume. His long yellow jacket has lighter markings on the front on each sides of his chest. He wears brown shoes, possibly boots, alongside black pants that mirror the appearance of his hat, having one large yellow line at the center going all the way down and wrapping around the bottom. He also wears other accessories such as a long cape that he sometimes takes off, black gloves, and a brown belt. Along with the other seekers, his face is constantly covered by his mask, making him a faceless character whose facial looks remains unrevealed at the time, shrouding his true appearance in mystery.

The design of his doll toy equivalents meant to mimic his attire is much less detailed, with only two features shared between the two costumes. They wear a long, large brown robe resembling a tailcoat with a big hood that covers the entirety of their body including their very small arms, adorned with mystical white patterns around it reminiscent of the ones on Arkham's shirt and jacket. Their faces are covered by a much smaller version of Arkham's signature white plague doctor mask.

A large amount of Arkham's dolls are hidden in the Toy Boxes pretending to be ordinary toys for The Baby. From the Sheep Chapter onwards, upon being spawned by the player from the Toy Box, the miniature doll toys will automatically follow the player around wherever they go if their back is turned, spying on the Sheep Sitter, indicating Arkham is either watching or will know the sitter's every move. They only move if the sitter is not looking (if they're out of the player's sight) and remain motionless whenever the sitter either looks at them or stops moving. There is also a childlike doodle drawing of a Doctor doll hanged on the wall of The Baby's bedroom, possibly drawn by the latter. More of the Doctor spies appear in the Rabbit Chapter, during The Exit level, observing the Rabbit Sitter as they run away from the baby, attempting to escape from Euclidean Towers. The first Doctor spy/spies can be seen in a small TV room located at the end of the long orange corridor during the déjà vu segment. The setting was originally just a bigger Doctor spy sitting on a sofa inside a locked room with its back turned to the glass door, watching a static television. After the release of the Dark Whispers update, this scene was upgraded to instead show a total of nine normal-sized Doctor spies on the floor with their backs turned, watching a glitching TV displaying a motionless image of Arkham's actual appearance in a reddish color. If the player notices the scene and approaches the room, Arkham's image then glitches completely and disappears from the TV, resulting in all of the small Doctor dolls turning around to look at the Rabbit Sitter instead from their spot behind the locked door.

As the three other members of the Seekers slowly began to fall victim to madness due to The King's influence, Arkham is presently forced to carry on their legacy as the last of his kind.[4] This is exemplified in the Log 901 he left near the gate of The Garden, which he concludes by stating, "In memory of the fallen, I must persevere." The exact circumstances surrounding his companions' downfalls remain shrouded in mystery, with the only specification being that they met their unfortunate fates before August 15th, taking into account Arkham saying "with no one else around, why not make the place my own?" in Log 633.

Due to having to remain as far as possible from The King's influence and never come into contact with it, Arkham's early-game appearances were originally very minimal despite being mentioned in the game since launch, and were almost all made in the form of his Doctor spy dolls. Presently, and from the Cat Chapter onwards, his appearances and mentions are no longer limited to those as this chapter takes place inside the Seekers' Laboratory, which allows the Cat Sitter to be able to find and collect several "Audio Logs," also known as "Memoirs of a Seeker," which are old audio recordings that Arkham left behind and scattered all around the Laboratory as reminders for himself in case he were to fall into madness and forget his duties. They serve as the primary source of knowledge regarding the events of the Seekers' story before the chronological beginning of the game. Some of them also document events that already occurred sooner as the game progressed, but from Arkham's point of view. With all Seekers specializing in a specific field, Arkham's field of research is alchemy, and his experiments revolve almost entirely around potion-making. He pursues his research in the Laboratory's Alchemy Room. At some point during their experiments and after major exposure to The King, Seeker Ambrose Armitage succumbed to The King's influence and ended up joining his ranks, which caused her to start antagonizing Arkham as the only person left trying to stop the cult of Hastur. She presumably broke the painting depicting her and her fellow Seekers displayed in her office to rip out Arkham's face only from the group portrait, making him unrecognizeable, and hovering over it will indicate "???" instead of his name like the three others despite the nearby plates set still showing his title. As part of the administrator verification process needed to access her desk computer, she also added the question "Who seeks to stop us?" and made the only correct option, "Nicolas."

As a member of the order of academics "The Seekers of the Jaundice Court" (also shortened to The Seekers), Arkham has dedicated his life to studying the dimension of Carcosa and The King in Yellow alongside his former colleagues Ambrose Armitage, Theodora Alhazred and Isadora Waite, who used to carry experiments and investigations together inside their main place of operations, an asylum in Carcosa known as The Laboratory. Arkham's main goal being to prevent The King's influence from spreading makes him a very careful and cautious person who, like his former co-workers, constantly wears a plague doctor costume to protect himself from falling victim to madness and corruption, and is determined to warn other people of the danger of coming into contact with The King, like Alice Pickman in the past, who had refused to listen to him. Operating in secrecy in order to avoid The King's influence as much as possible,he eventually started fabricating an unknown but vast amount of miniature, mobile, plush-like robotic dolls of himself in order to spy on the "Yellow Sites," the areas dominated and influenced by The Baby, to gather information without having to go to the location in person. These spy dolls are able to move freely and operate by discreetly visiting Yellow Sites to take pictures of important information to bring back to Arkham. The third door marked "III," located on the left side of the 'Newt boosters' area in the Laboratory's basement, leads to a smaller room with two desks which he presumably used when fabricating or fixing his dolls or keeping them under maintenance. Along with the audio recording of Log 285 and a tool box are two normal Doctor dolls next to a laid down broken Doctor that Arkham was possibly fixing, and a single shelf on the right. On said shelf is placed a guide book titled "Doll Making Volume IV" which he was seemingly using to help with the creation and development of his dolls.