Counter Strike Online Wiki
I become like this all because of you.
— Jack's words in Memories chapter

Jack is a boss in Memories chapter in Counter-Strike Online.


Zs memories3 cso

Jack was one of the escapees from Rex Laboratory after the zombie virus outbreak incident alongside Jennifer. Unfortunately, he failed to escape while on the go and suffered from the zombie virus, mutating into an evil abomination seeking for revenge with Jennifer becoming one of his targets for the lost cause. He also assassinated Laser Wing and use Jennifer behavior to lure her to his presence.


  • Normal attacks:
    • Ground punch
    • Direct punch
    • Slash
  • Warp attack: Move instantly to the target and attack.
  • Toxic jump: Jump to higher place and flood the lower area with toxic. The player must find the indicated pipe to flow away the toxic.
  • Shock wave: Send a harming sound wave to the target.
  • Shoots with an M134 Minigun Predator
  • Rocket throwing


  • Whenever he gets up to a high place to perform certain attacks, his body will be covered in a white glow which indicates that during the movement he will be invulnerable.


Honor mission[]

Title Description Task
A medal given to people who defeat the former colleague Jack.
Gentlemen, today's friend is tomorrow's enemy. Can you really totally trust in your colleague of yesterday? Note: only counted in room with 4 players and above, easy stage is not included. Defeat Jack 100 times in Memories chapter.



  • As a human, he resembles Gordon Freeman, the protagonist of the Half-Life series. As a zombie, he resembles characters from other games, notably the Tyrant T-002 and the first two forms of mutated William Birkin from Resident Evil series.
  • If any player stands on the spot where he lands, he or she will be killed instantly.
  • When the boss is hurling rockets and launching minigun attacks, he is invulnerable to any damage.
    • However, there is a bug where if a player uses Bendita to shoot Jack when he's invulnerable, he/she could still damage him. This bug was fixed after Zombie Scenario 2016 patch.
    • There is another bug where sometimes when Jack jumps on to the high place of the boss room, he will be stuck (cannot jump down), which makes him "invulnerable".
  • There is some bug when Jack will jump but he near in barrels, he will be stuck (cannot jump), which makes him "invulnerable".
  • Some skills of the boss may be inspired from Goku's skill from Dragon Ball series; mostly observed with the Instant Transmission and Kame Hame Ha skills.