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.

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.

Betrayal
At the end of the game, after defeat the Spider Mastermind, Samuel Hayden activates the dimensional tether and pulls Doom Slayer back into the UAC facility. He proceeds to tell Doom Slayer that they have won, but at a cost of the entire UAC operation. He then reveals he has been watching them, and has determined their motivations differ, in that Doom Slayer believes Hell must be destroyed entirely, and while Samuel admits that they may be right, 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 some sort of red energy blade, and Hayden states that while he can't kill them, he would not allow them to stand in his way, and uses the dimensional tether to teleport 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.
 * He keeps statues of the Night Sentinels and Praetor suit in his office.