Four years prior to the events of Crysis, in the year 2016, Nomad, Psycho, and O'Neill were involved in an unspecified training mission related to placement in the top secret US Special Forces group called Raptor Team. O'Neill triggered a "Code Blue," military jargon for someone needing resusciation, often as a result of cardiac arrest. Indeed, a flatlining noise can be heard in the background during a recording of these events. Psycho angrily tries to convince O'Neill to stop an unknown action, apparently related to a warhead, which is endangering Nomad's life. As a result, O'Neill was discharged from the US Special Forces and Nomad took his place in Raptor Team.

During Crysis Warhead

On August 15, 2020, O'Neill was pilot in the US Navy and assisted in the invasion of the island. O'Neill was assigned to provide to help Psycho, and was eventually shot down by two enemy Su-27 Flankers. Psycho went off mission to rescue O'Neill, much to Emerson's annoyance. O'Neill later tried to convince Emerson to let him use a VTOL to extract the Alien Scout container that Psycho had been assigned to secure. Emerson reluctantly agreed when Psycho convinced her that O'Neill would be suitable for the mission. O'Neill ran out of ammo and became seperated from Psycho. During this time, O'Neill was ordered to evac, and Psycho was nearly killed by Colonel Lee Kim Sun as he was expecting O'Neill to extract the container. Psycho seemed to resent O'Neill for not being there to assist, but eventually forgave him.

During the final battle at the airfield, O'Neill used his VTOL to distract the Red Hunter while Psycho attempted to destroy it with the Plasma Accumulator Cannon. While O'Neill began loading the container on his VTOL, they were confronted by Lee, who tried to shoot him. However, a cloaked Psycho shielded O'Neill. As O'Neill began to pilot the VTOL with the container away from the airfield, Psycho and Lee fought in the troop compartment. Psycho eventually defeated him, leaving him to the mercy of the Alien Warrior. Psycho forgave O'Neill for the code blue incident, Emerson and O'Neill appeared to have set aside their differences. O'Neill then proceeded to pilot the VTOL back to the carrier fleet. O'Neill's fate after that is unclear, it is not revealed if he survived the battle on the USS Constitution or not.


  • I'm one man with a pistol against the entire KPA, send a ****ing pick-up!! - Sean O'Neill, Shore Leave, after being shot down and crash-landing in enemy territory.
  • I don't believe it! Those son of a ***** mechanics short-changed me! I'm out of ammo! - Sean O'Neill, From Hell's Heart, when running out of ammo while aiding Psycho from a VTOL.
  • Yeah search-and-rescue whoop-de-****ing-doo - Sean O'Neil, From Hell's Heart, after Psycho told him that he is now search-and-rescue.
  • Just forget about it, man! I would have been there if I could! - Sean O'Neill, All the Fury, trying to explain to Psycho why he wasn't at the bridge earlier.
  • We're coming home. - Sean O'Neill, All the Fury, when leaving Lingshan Islands with Psycho and the Container.


  • While following Psycho to meet Admiral Morrison in Reckoning, there's a guy wearing sky blue jacket that looks exactly like O'Neill, except his face is now clear from wounds.
  • In Reckoning you can see a VTOL taking-off, it's a possibility that it is O'Neill.
  • O'Neill is the only soldier not wearing a Nanosuit, to survive throughout an entire game (Crysis Warhead).
Characters in Crysis and Crysis Warhead
KPA Lee Kim-sun · Kyong Ri Chan
Other Edward Jones
Raptor Team Aztec · Jester · Nomad · Prophet · Psycho
Eagle Team Bandit · Bear · Blue Dog · Cupcake · Dane
Research Team Martin Badowski · David Rosenthal · Helena Rosenthal · Hostage
US Military Richard Morrison · Clarence Strickland · Sean O'Neill · Emerson · Tim Gillespie · Lieutenant Bradley

Community content is available under CC-BY-SA unless otherwise noted.