Samuel Hayden

Samuel Hayden is the Chairman of the UAC who oversaw the Argent energy research projects at the UAC Mars Base. A supporting character in Doom (2016) and Doom Eternal, he helps guide the Doom Slayer.

History
Samuel Hayden was born to the powerful Hayden family and was a very prodigious intellectual and philanthropist. After he was appointed as General Director of the Global Science Council, the UAC recruited him. Soon after Argent energy was discovered on Mars, Hayden subsequently took over the leadership of the UAC.

After the Argent Tower was constructed in 2127, Hayden was diagnosed with an incurable brain cancer and left with a few months to live. Hayden avoided his death by transferring parts of his brain into a 3-meter tall mechanical body. It was implied that Hayden chose this form for his expeditions into Hell.

Hayden led the first manned expedition into Hell in 2145 in which he discovered the Doom Slayer, simply called "Doom Marine". He had the Marine recovered and kept him personally under his watch away from the auspices of his disgruntled colleague Olivia Pierce. Hayden's relationship with Pierce gradually deteriorated due to her deranged, religious obsession with Hell which ultimately corrupted her.

Doom (2016)
After Pierce betrayed Hayden and planned to open the gates of Hell, Hayden awakened the Doom Marine and tried to persuade him to assist him in stopping Pierce. However, he is harshly rebuffed twice at the beginning of the game, though Hayden claims to be willing to accept full responsibility for Hell's invasion. Hayden was able to gain the Marine's partial cooperation after cutting off his access to the satellite communications array and offering information that he seeks, although in their attempt to stop Pierce, the Marine later destroyed the Argent energy stations rather than temporarily disabling them as Hayden asked, much to Hayden's irritation.

Hayden eventually meets the Doom Marine face-to-face in his office following the latter's return from Hell and the destruction of the Argent Tower. He explained to the Marine 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, an artifact that can control the source of Argent energy known as "The Well," and stop Pierce's plans. He instructed the Marine to go to the Lazarus Labs to find the Helix Stone and a powerful weapon.

But Hayden also intended to restart Argent energy production as soon as possible, but also knew the Marine would disapprove, as he demonstrated by his testy behavior at the Argent Facility. After the Doom Marine killed Pierce and stopped Hell's invasion, Hayden summoned the Marine to the facility via a dimensional tether. He then traps the Doom Marine, taking the Crucible from him to continue exploiting Hell's resources for the sake of humanity's progress. Hayden admitted that he cannot kill the Doom Marine, but he will not allow him to stand in his plans, before teleporting the Doom Marine to an unspecified location. Before he does so, however, Hayden states his certainty that he and the Doom Marine would meet again.

Doom Eternal
In 2150, Hayden suddenly resurfaced on Earth before the Allied Nations Council during the time the demonic invasion of Earth had already begun. Hayden recounted the events on Mars to the AN Council before offering to help lead humanity against Hell by providing them his technologies and the Crucible, the last remaining source of Argent Energy in existence.

The Council appointed Hayden as the Lead Director of the Armored Response Coalition. Under his leadership, Hayden re-purposed the UAC facilities on Earth to produce and supply Argent technology and advanced armaments to the ARC. As the war against Hell grew more dire, Hayden was subsequently given full command over all resistance efforts. With humanity deprived of its Argent-dependent energy grid after the loss of the Well, Hayden invented a method of Argent-Synthesis, a synthetic replication that could recreate the high-yield capability of Argent Energy. Using the Crucible's hidden power, Hayden utilized the artifact as an Argent conductor to restoring the production of Argent energy to Earth.

Hayden later fell in battle during Operation Hellbreaker, a powerful counterattack that he planned and ultimately ended in failure. His robotic torso, which suffered the loss of its right forearm and legs, was retrieved by ARC soldiers. Hayden was tended and monitored by a skeleton crew of scientists, who safeguard his body along with the Crucible, in the ARC Complex. The scientists were unable to revive Hayden as they have no knowledge to access his main cortex due to its "alien" make up.

The Doom Slayer, on the advice of VEGA, sought for Hayden's aid in finding the location of the final Hell Priest, Deag Grav. Upon the Slayer arriving at the facility, Hayden had long anticipated for the Slayer's return and specifically told his caretakers to give the Crucible to the Slayer. When the Slayer reunited with Hayden, he roughly took the torso and threw him into a portal to the Fortress of Doom. There, Hayden's consciousness is transferred into the Fortress's mainframe, as his body is similar and compatible to the architecture, and awoke. From there, Hayden then explained to the Slayer of Deag Grav's whereabouts in Sentinel Prime and that getting there is through the only functional slip-gate, located in the core of Mars, in the lost city of Hebeth. Though Hayden voiced his concerns on the difficultly of gaining access to the core of Mars, he is exasperated over the Slayer's direct approach to use the BFG-10000 to shoot a hole into Mars' surface. Following afterwards, Hayden guided the Slayer throughout his journey.

After the Slayer killed Grav, the Khan Maykr attempted to stop him by shutting down the Fortress of Doom. However, the Slayer the Crucible's latent Argent energy to reactivated the fortress. Hayden was left amused by the irony of the Crucible's very power source that the Slayer sought to eradicate from Earth became his aid to save it. Hayden then helped guide the Slayer in retrieving his own Crucible to slay the Icon of Sin and stopping the Maykrs from consuming Earth.

Trivia

 * Despite having been diagnosed with "incurable brain cancer", Samuel Hayden had his frontal and temporal lobes transferred to his new body. It is possible that these parts of his brain were free of cancer, and that he chose to replace his whole body rather than simply replace the cancerous parts of his brain with cybernetic equivalents.
 * Hayden's original human form can be seen in a hallway showing various scientists.
 * Hayden is possibly immune to aging since his body is constantly maintained by stem cell and neuro-maintaining agents. However, he is not invincible. Currently, he is over 130 years old.
 * S. Hayden has a phonetic similarity to "Satan", which may be foreshadowing that Samuel Hayden might be allied with the forces of Hell somehow (similar to Dr. Betruger of Doom 3). This appears to not hold true as of Doom Eternal, and so may be a mere coincidence.
 * When Hayden walks away to his office, the player is given control of his weapons, and can shoot Hayden. However, the bullets strike an invisible force field of sorts, dealing no damage to Hayden, who simply shrugs it off while telling the player to save their ammunition.
 * His name is taken from a character cut from the Doom 3, but also appeared in the Doom 3 novels: General Hayden. Their personalities and history are not similar however, and only the name is recycled. It would also seem unlikely that they are related.
 * Samuel Hayden along with the Doom Slayer are the only human beings to have survived a trip to Hell and back.
 * Hayden's ability to control the Doom Slayer is reminiscent of the G-Man's control of Dr. Gordon Freeman, the protagonist of the Half-Life series.
 * Doom Eternal alludes to a possibly otherworldly origin for Samuel. The Seraphim, Samur Maykr shares the same voice actor as Hayden, and the ARC scientists state that Samuel's body is "alien" and that they can't figure it out. Similarly, when brought back to the Fortress of Doom, VEGA states that Hayden's body has similar a architecture to the ship, suggesting he is of Maykr design. VEGA glitches out for a second when connected to the mainframe of the Maykr capital, asking "Am I the Father?", suggesting that 'the essence of the Father' that was stolen from the Maykrs may very well have been used to create VEGA.
 * This can also be seen as both characters share a near-exact quote with each other. While Hayden in Doom (2016) states "It's a gift. Take it, it will give you strength, help you on your journey..." after giving the Slayer an Argent Cell, the Seraphim, before granting the Slayer his powers, states "I offer you a gift. Take it. It will give you strength... help you along your journey."