ISAAC CLARKE
The main character of the game. Isaac is a systems engineer traveling aboard the shuttle Kellion to investigate and repair the USG Ishimura in company with three security personnel and a computer specialist. Unfortunately for them, they are thrust into the middle of the nightmare that the USG Ishimura has become. Clarke is also trying to find his Ex-girlfriend, Nicole, a medical specialist assigned to the ship, whose fate is unknown at the start of the game. Throughout the game Isaac stumbles onto something much bigger than him involving the Church of Unitology, the government and the realm of possibilities. Through logs activated after clearing the game we learn that Isaac's father, Paul Clarke, left for space when he was just a child and the anguish of losing her husband made his mother, Octavia Clarke, into a devout Unitologist who gave all her money to the church rather than finance her son's education. He went to a lesser-known college than the one he strives for but graduates with high honors, taking after his father and becoming a system engineer.
KENDRA DANIELS
Kendra is a technology expert and part of the team sent aboard the Ishimura once the ship goes silent. She helps the player through the Ishimura in many ways, giving directions and assisting through areas of the ship that would otherwise be inaccessible. She frequently expresses distrust of Hammond, but turns out to know more about the situation than anyone previously thought. In a log after clearing the game, it is stated that she was hand picked for the mission by higher-ups.
ZACH HAMMOND
The senior security officer on board the Kellion who travels with both Isaac and Kendra to the Ishimura. Hammond's initial desire to complete the original mission and not immediately abort puts him at odds with Kendra, who finds this suspicious. Throughout the game he works to fulfill their original mission, but as time goes on, he becomes more disillusioned and focuses instead on getting himself and the rest of the surviving team off the ship. In a log after clearing the game it is revealed he asked for the information for both Isaac and Kendra, though the reason for this inquiry is not revealed.
Dr. Challus Mercer:
A doctor aboard the USG Ishimura and a devout Unitologist. In the wake of the calamity that has gripped the Ishimura, Mercer has become a religious fanatic, and attempted to convince the crew of the Ishimura to commit mass suicide. Mercer often works to bar the progress of Isaac and even attempts to kill him outright. Mercer sends a 'prototype,' regenerating Necromorph after Isaac several times through the course of the game until Isaac finally manages to kill it. To Mercer, everything that has happened is God's will, and Isaac should die and allow their 'children' to take over. Near the end of the game, Mercer willingly sacrifices himself to a Necromorph, believing in his religion and its requirements that he die before he reaches the next level of evolution as a Necromorph himself.
Dr. Terrence Kyne:
he Chief Science Officer of the Ishimura who appears later in the game and asks for help from the surviving members of the Kellion team. He seems to be a bit eccentric, perhaps deranged, but offers to aid Isaac in stopping the nightmare that has gripped the Aegis System and the Ishimura. Kyne attempted to relieve Captain Mathius of duty during the crisis on the ship but instead seems to have been complicit in the captain's death either in whole or in part. He regularly interacts with his dead wife, an apparition caused by the Marker that can't be seen by the player.
Nicole Brennan:
Isaac's ex-girlfriend and a medical specialist assigned to the Ishimura. She sent him a video asking for help and is one of the reasons he came to the Ishimura. He both sees and hears her as he moves through the ship and she repeatedly asks Isaac to "make us(/them) whole again," however, something isn't right about her.
Jacob Temple:
Jacob is an engineer on the USG Ishimura who is, like Isaac, trying to find his own girlfriend, Dr. Elizabeth Cross. The player often finds audio logs left behind by him as he progresses throughout the game. They find each other in the crew quarters but their reunion is cut short by Doctor Mercer. Temple never makes direct contact with the player. Isaac comes across Several of Jacob's audio recordings throughout the game, especially in chapter three, where Isaac must travel down to engineering.
Captain Benjamin Matthius:
The captain of the Ishimura. Matthius was revealed to be a Unitologist who is strong in the belief the Marker belongs to the church. His fate is shown in a video log found on the fourth Level. He redirected the ship to collect the Maker and was experiencing dementia like so many of the exposed. He is relieved of duty by Dr. Kyne. He was killed when Dr. Kyne accidentally stabbed him in the eye with a hypodermic needle. He is later resurrected into a Enhanced Slasher by an Infector, and is the first one you fight in the game.
