Samuel Hayden

General Hayden is the commandant of the UAC space marine garrison in the Doom 3 novels. In the reboot, he is now an advanced cyborg going by the name Samuel Hayden, who is the chairman of the UAC and highest command on Mars.

Doom 3 Novels
Hayden is a human being with bronzed face officer's spawn and artificial sun. He is opposed to Swann and Campbell's investigation of the Mars facility, warning them that Betruger won't let them pull the plug on his operation.

Doom 2016
Samuel Hayden appears again n the reboot and tries to persuade the protagonist, simply called "Doom Marine", to assist him. 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 takes the role as a supporting character throughout the game, eventually revealed to have had parts of his brain transferred to a mechanical body after having been diagnosed with incurable brain cancer in some parts of his brain. Hayden eventually betrays the Doom Marine, taking the "crucible" artifact from the player before sending the Doom Marine straight to hell. Before he does so however, Hayden states his certainty that he and the player would meet again. It is possible that Samuel Hayden will appear in future Doom titles, possibly as an antagonist.

Trivia

 * He was slated to appear as a secondary antagonist in Doom 3, but was cut from the game, making Betruger the main antagonist.
 * 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 choose to replace whole his body rather than simply replace the cancerous parts of his brain with cybernetic equivalents.
 * It is possible to see the original Human Hayden in a hallway showing various scientests.
 * It is stated in-game that Samuel Hayden choose to make his body so large and powerful (being approximately 3 meters tall) because of how dangerous he thought his job and position were.