Samuel Hayden

Dr. Samuel Hayden is a character in the Doom, a high-ranking UAC official who oversaw the Argent energy research projects at the UAC Mars Base. After an unknown incident during construction of the facility's Argent Tower which caused him to develop brain cancer, he was forced to replace almost the entirety of his body with cybernetics. He was first officially shown by id Software in the game's official launch trailer greeting the Doom marine after he awakens from an apparent slumber. In exclusive footage released by video card manufacturer to demonstrate the performance potentials of the then-new  graphics API in id Tech 6, he can be heard acting as an advisor to the marine, speaking about Olivia Pierce, to whom he is now an enemy. He states that he had hoped she would "rise above their influence," referring to the demons from Hell which she instead unleashed.

Hayden is adamant in defending his original research projects into Hell and its Argent energy reserves, stating that it was all in mankind's best interest, and that the sacrifices made would have been worth the cost, if his other staff had been able to resist the corrupting influences of the demonic dimension. While he seems friendly, whether or not he can be trusted must be regarded as a question.

Samuel Hayden's voice acting is performed by Darin De Paul.

Background
Samuel Hayden received his first degree, a Masters in Theoretical Physics, at Oxford University. Rising to prominence as a renowned scientist, he created his own foundation to fund up-and-coming young scientists and educational programs in schools. After being appointed the General Director of the Global Science Council, he was offered leadership of the UAC mere months later. After the discovery of the Argent Fracture on Mars, he put plans for the Argent Tower into immediate production.

During the construction of the tower, he was diagnosed with terminal stage 4 brain cancer, and put all of his efforts toward devising a scheme for his personal immortality. The end result of this effort was the transference of his brain into a ten-foot-tall, powerful cyborg body powered initially by Argent caches and eventually by an Argent accumulator. As of the time of the invasion of the UAC Mars Base, Samuel is over 130 years old, and is expected to live indefinitely.

Though spared from death by his actions, Samuel was demoted to Project Director of the Argent facilities due to his new appearance and nature being too controversial for him to act as the public face of a global megacorporation. After development of the Global Energy Distribution Matrix and a globally live-streamed event showing Samuel throwing the switch to send the first Argent energy packet to Earth, however, it became clear to everyone that he, as the only one who could "turn on the power," would wield enormous influence regardless of his official position.

Recruitment of the protagonist
Hayden meets initial resistance from the Doom marine when trying to recruit him to fight against Olivia and stop her planned opening of the portal to Hell in his preferred manner, with the soldier violently destroying every device he tries to use for communication. Dr. Hayden ends up forcing the marine's hand by cutting off his access to the satellite communications array and offering him the information he seeks in exchange for his cooperation. Once actively allied, Hayden has VEGA give the marine access to all of the facility's Argent energy capsules.

Argent Tower and fallout
Samuel is met in person after the destruction of the Argent Energy Tower and the marine's return from the Kadingir Sanctum in Hell. He has the marine take the monorail to the Advanced Research Complex to visit his office. When the marine touches the door panel, however, he receives an unexpected electric jolt and finds that an interdimensional travel device called a tether, used extensively by the UAC to bring objects and demons back from Hell, has been forcefully installed into the Praetor suit. Samuel dubiously apologizes, stating that he did not believe the upgrade would have been willingly accepted despite its necessity.

Samuel discusses the destruction of the tower, referring to the way in which the marine permanently disabled it against his wishes as regrettable. He also speaks about the ongoing demonic invasion of the facility through the still-open Hell portal, and the need to pursue a new way into Hell in order to locate the Crucible, a device that can control the source of Argent energy known as "the Well," and stop Olivia's plans from continuing any further. He states that the marine needs to proceed on to the Lazarus Labs to find a relic from Hell called the Helix Stone, and notes that, given his propensity for firearms, he should also be able to find a powerful weapon there.

End-game
At the end of the game, after defeating the Spider Mastermind, Samuel Hayden activates the dimensional tether and pulls the Doom Slayer back into the UAC facility. He proceeds to tell the captive marine that they have won, but at a cost of the entire UAC operation. He then reveals he has been watching, and has determined their motivations differ, in that the Doom Slayer believes Hell must be destroyed entirely, and while Samuel admits the possibility this is true, he believes humanity needs Argent energy. He then steals the Crucible by somehow pulling it through the air into his hand, stating that with it, he can continue his work. The Crucible then turns into a red energy blade enscribed with runes, and Hayden states that while he cannot kill the marine, he would neither allow him to stand in his way, and uses the dimensional tether to teleport the Doom Slayer to an unknown location before the end credits start to roll.

Character origins
The original plans for Doom 3 called for a character named General Hayden to function as a secondary villain, initially appearing to be the cause of the invasion and taking the place of Dr. Malcolm Betruger in several of the game's scenes, only for Betruger to be later revealed as the true mastermind. While dropped from the game, with his roles dispersed between those of Betruger and Sergeant Kelly, he was retained and revived in the Doom 3 novels.

Trivia

 * When meeting him in his office, his right hand has blood spatters across it, implying he had to kill something, but his office is completely clean and white.
 * Hayden's cyborg body seems impervious to conventional firearm damage. If the player attempts to fire at Hayden as he is walking into his office, Hayden will remark, "Save your ammunition," while taking no damage.
 * Adding on to Samuel's dubious nature is that a good portion of his mind and the entirety of his physique aren't natural; in addition to his cybernetic body, his Codex entries state that he has replaced or hyper-accelerated several parts of his brain not related to his personality to grant himself super-intelligence.
 * He keeps statues of the Night Sentinels and Praetor suit in his office.