Challus Mercer
Biographical information

Date of death:


Physical information




USG Civilian RIG





Chronological and political information




"Your future, the future of our race ends here!"
—Dr. Mercer talking about the Necromorphs

Doctor Challus Mercer was a scientist aboard the USG Ishimura and a devout Unitologist to the point of zealotry. Mercer became fanatically obsessed with the Necromorphs after the Ishimura was compromised and the infection spread. Mercer believed that the Necromorph infection was the next stage of the human race and their ability to reanimate necrotic flesh was life after death.


The Second Aegis VII IncidentEdit


"I hope one of his beloved Necromorphs finds him before I do."
Isaac Clarke: Chapter 5 mission log

Challus Mercer performed several medical experiments on the crew of the USG Ishimura, one of which resulted in the Hunter. While ordinary Necromorphs are usually produced by the infection of corpses, audio logs suggested that Mercer's experiments are aimed at transmitting the infection to live subjects which caused the Hunter's unique regenerative properties. When Isaac Clarke encountered Dr. Mercer, Mercer appeared to be psychologically unstable. He advocated mass suicide among the crew and kept severed human body parts in his office. He viewed the human race as obsolete in the face of the Necromorphs, even to the extent of assisting the infection by way of deliberate sabotage to the ship's systems. He viewed Isaac Clarke's struggle to survive as admirable, but misguided and attempted to kill him on several occasions by having the Hunter attack Isaac and shutting off the life support systems in the sections of the Ishimura that Isaac traveled through. Mercer was also responsible for murdering the fellow crew members named Jacob Temple and Elizabeth Cross.


Mercer and infector

Mercer getting mauled by an Infector

"Your time has come. No need to be frightened. No reason to fight. Many have gone before us, and now it's time for us to take the voyage together, to transcend death... and let the future take its course. Join me, as I gaze upon the face of God!"

After Isaac defeated the Hunter, Mercer allowed himself to be killed by an Infector, becoming a Necromorph himself —an Enhanced Slasher.[1] Isaac Clarke encountered the changed Mercer and euthanized him.[note 1]


Before his descent into madness, Mercer was a loyal and hardworking crew member aboard the USG Ishimura despite being a devout member of the Church of Unitology. After the Necromorph outbreak, Mercer became insane and attempted to aid the Necromorphs in their assault on the ship, believing that they are sent by God to destroy humanity. He sided with Captain Mathius in the belief that the Red Marker was a holy artifact, but could tell that Dr. Kyne wanted the Marker away from the Ishimura. In an abandoned log tape, Mercer revealed that, while Dr. Kyne was studying the Marker to find a means of ending the infection, Mercer himself was experimenting on live crew members to create stronger Necromorphs.

Mercer showed no interest or sympathy in the survival of the Ishimura's crew. He praised Isaac Clarke for surviving snare after snare, but believed that all attempts to survive on Clarke's part are pointless. Mercer also had very little humanity as he performed trepanation on a conscious crew member in order to directly infect them while they lived. He also bored holes into the skulls of the dead crew members to ensure easy infection.


  • Iranian-American actor Navid Negahban provides the voice and likeness of Challus Mercer.
  • It is interesting to note that he knows about the Hive Mind, exposed in Chapter 5 where he clearly asks Isaac "not to spurn the Hive Mind's offering", referring to the Necromorph infection. However, it is later revealed by Kyne that Mercer was the one who named the creature in the first place.
  • He is believed to be responsible for sabotaging the USG Ishimura's escape pods.
  • It is a mystery as to how Mercer managed to survive for so long after the infection spread to the ship, let alone how he managed to move around the ship without being attacked by the Necromorphs. Though it is speculated that Necromorphs do not attack those who are under the influence of the Marker. It's also possible that, since he was actively helping them as a human, the Necromorphs didn't see a reason to turn him until he desired it, or until his human form served its purpose fully.
  • Of all the people on the ship, Mercer seems to be among the most insane: he creates The Hunter from a living subject in his quest to understand the Necromorph "gods". His freezing of Necromorphs to bring back to Earth, intending to make sure the human race was transformed into Necromorphs, is a further example of the depths of his madness.
  • Mercer appeared confident in his plan to take the frozen necromorph specimens back to Earth, despite the heavily deteriorated condition of the ship by then, leading to the possibility his delusion was stronger than initially implied.
  • Though it's unlikely, it is still possible that Mercer may have been the one blocking Hammond's RIG, given that he was knowlegable enough to reprogram door locks and turn off life support systems.
  • It is interesting to note that, although Mercer was insane, he was still able to point out those who were under the influence of the Marker, as he did when detailing how Dr. Kyne mentioned speaking to his wife—noting that "Amelia Kyne has been dead for several years".
  • Often, Marker relics are found near Mercer; the first is the small Black Marker in his office and the second is the slightly larger variant of this ornament on a table near the place of his death on the Crew Deck.
  • A book entitled "Field Medicine" with the logo of the USM Valor, a military vessel that appears in Chapter 8 and 9, can be found in one of Mercer's laboratories on the Medical Deck.
  • If the player kills Mercer following infection, a short, strident segue of music is played to denote the event.
  • Challus Mercer is the first human antagonist of the series, if we except the double-dealing of Kendra Daniels.
  • If the player acts fast enough, the Infector Mercer submits himself to can be killed before fully infecting him, both preventing the need to fight him as an Infector and ultimately robbing him of his final wish, though this has no impact on the game's story one way or another.
    • Strangely, in the last video log, it is seen that Mercer is perfectly fine when he gets killed by an Infector. However, as Isaac approaches the Infector and Mercer, the Necromorph is just getting ready to infect the corpse. He should've already been transformed by the time Isaac gets there.
    • If the Infector is killed before it can convert him into a Necromorph, Mercer's body is totally mutilated, bloody with bone and muscles visible as well as his head missing (this could be interpreted as a nod to Mercer's "blind faith"), even though in the earlier log it was clearly seen that Mercer was totally fine. The model is in fact merely a generic Ishimura crew model.
    • Like Captain Mathias, the resulting Enchanced Slasher from Mercer's body is in no way special from the others encountered in the game.
Spoilers end here.



  1. If the player is fast enough, the Infector can be killed before the transformation can be completed. It’s possible to decide to just let Mercer turn into a Necromorph and leave him be and give him what he wants, but when the Marker is destroyed the signal is stopped thus killing the infected Mercer and then he collapses and becomes sludge.