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The greasel is a transgenic creature that appears in Deus Ex and Deus Ex: Invisible War.


Greasels were created by VersaLife through genetic engineering; thus, they are a type of transgenic creature. Their characteristics include hypotrophic wings, a spitting-cobra morphology, and muscles enhanced by V-actin.[1] Their spit affects the human nervous system to the effect of impaired coordination and vision.[2]

Greasels were frequently studied at Majestic 12 facilities, such as the Liberty Island MJ12 lab, the VersaLife facility in Hong Kong, and the Pasadena Ocean Lab. In the Denfert-Rochereau in Paris, a group of greasels seemingly escaped, or were deliberately released, from a nearby facility.

Antarctica VersaLife base[]

VersaLife personnel at their Antarctica base created a new breed of greasels, known as red greasels, through the infusion of additional genetic material. Red greasels were meaner and tougher.[3] They were also more attractive to female greasels than their green counterparts.[4]

Following the collapse, many greasels escaped from the VersaLife facility in Antarctica.[5] A group of unlucky scientists who became trapped in JC Denton's Sanctuary encountered a pack of escaped greasels that slowly hunted them until none of the scientists remained alive.


In 2072, despite the danger that greasels pose, they are sought after by certain segments of post-Collapse society. Some greasels are kept as pets. According to one price list, greasels are sold as exotic pets at a price of 350 credits.[6] A training manual, titled "Greasel Care," states that greasels should be kept in cages and should eat a whole cat each day.[7]

In Lower Seattle, greasel fights have become a popular attraction at the "Greasel Pit Bar," where an intrepid trainer (or a smart gambler) can make considerable amounts of money with the right greasel. The current champion is Gobzilla, whose trainer is Tina.


Deus Ex[]

In Deus Ex, greasels are part of the Animal class of scripted entities. They are usually hostile to the player, and will attack using their toxic spit (WeaponGreaselSpit), which inflicts poison damage and damage-over-time. The greasel spit is similar to the tranquilizer darts of the mini-crossbow, except that it has a base damage of 8 (for both the direct hit and damage-over-time ticks), which is higher than the tranquilizer dart's base damage of 5.

Greasels have full immunity to riot prod and all gas damage types. Greasel are also capable of swimming, with an unlimited oxygen duration while underwater. Their ranged spit travels underwater in the same manner as it does through air.


A greasel eating a body


  • Caged greasels in the Liberty Island MJ12 lab can released via button or computer, causing them to attack all humans in the area, including the player.
  • Greasels in the VersaLife facility in Hong Kong can be released, causing them to befriend the player and attack MJ12 in the area.
  • Greasels are found in Denfert-Rochereau, Paris, and are part of an optional objective.
  • Escaped greasels can be found in the Pasadena Ocean Lab after the attack on the facility opened their cases and
  • Greasels are created by Universal Constructors in Area 51.

Deus Ex: Invisible War[]

Greasels are a type of hostile creature in Invisible War. They are armed with a spit attack, which a damage-over-time effect.

Red greasels are mentioned in Invisible War, but do not appear in actual gameplay. The Red Greasel Hunter is a unique pistol in Deus Ex: Invisible War specially modified by the Omar to hunt greasels.

Prerelease concepts and cut content[]

In Deus Ex design document version 13.12, greasels are named "Greazels" and are said to be a "genetically manipulated, nano-augmented seagull." The concept of nano-augmented animals was proposed for several types of animals, but was generally cut from the final game. The detail of being derived from seagulls is not explicitly mentioned in the final game.

The design document also states that Greazel venom is incapable of actually killing a victim; for this reason, Greazels rely on Karkians to finish off their prey. This statement is consistent with the gameplay design that poison damage is non-lethal when inflicted upon a non-player character (however, in Deus Ex, non-lethality only applies to non-player characters, and does not apply to the player character).


Size: Medium (turkey sized)

Demeanor: Flock mentality. Easily frightened when alone; hostile in groups.

Description: Genetically manipulated, nano-augmented seagull. Greazel look like seagulls devolved back to their dinosaur origins. Feathers cover the wings, allowing flight, but the rest of the body is covered in dinosaur-like quills or spiky fur. They have no teeth but their sharp beaks can inflict a bit of damage. (However, the beaks are designed more for pecking and digging out chunks of meat from dead animals).

Location: Found in Majestic 12 nano-labs, particularly VersaLife. Not really a threat unless released from their pens. Then they can threaten the PC or be unleashed on unsuspecting NPCs. If released, Greazels will do everything in their (limited) power to get to and/or stay with a Karkian.

Role: Greazels are like nano-rats with wings and were created as part of the same experimental program. Designed as a super-scavenger for use in cleaning up large open areas or shallow water areas. The end result was something the researchers never anticipated: a bio-weapon capable of incapacitating its victims.

Combat Notes: The Greazel incapacitates victims by flying above them and regurgitating caustic, venomous globules on them. The venom, absorbed through the skin, blurs the victim’s vision and affects aiming ability and movement speed. What they can’t do is actually kill a victim. For this reason, they’ve developed a symbiotic relationship with Karkians. They disable their target and then flank, land on and/or huddle behind a Karkian, waiting for it to make the kill on the helpless victim. Then, they scavenge whatever remains of the kill when the Karkian is done.

Deus Ex design document v. 13.12

Cut content in Deus Ex: Invisible War similarly references the greasel's avine origin, as well as its symbiotic relationship with karkians.

Greasels were created via the de-evolution of avine DNA to it's dinosaur origins. They share a flock mentality and are hostile in these groups, but easily frightened when alone. They attack by spitting a caustic venom that blurs the vision and affects the physical coordination of their prey. They possess an unexpected symbiotic bond with karkians, and when attacking in the company of one, they will disable their target, then flank, waiting for the karkian to make the kill. Then they will scavenge the remains when the karkian has finished feeding.

Museum of Nanotechnology guide (Deus Ex: Invisible War cut content)

Baby greasels were planned to appear in Invisible War but were never featured. The file for the greasel model has the "_Adult" suffix, but a baby version does not exist in the released game. Dialogue for NPCs fighting baby greasels exists in the file.

See also[]



  1. See "Greasel Disection" image, from a datacube in the Liberty Island MJ12 Lab.
  2. Lab Notes, Dr. Moreau
  3. "Red Greasels, Next Rev" (datacube in Deus Ex: Invisible War)
  4. "Project RedRover" (datacube in Deus Ex: Invisible War)
  5. "Fenning's Journal" (datacube in Deus Ex: Invisible War)
  6. "Galleria Pets" (datacube in Deus Ex: Invisible War)
  7. "Greasel care" (datacube in Deus Ex: Invisible War)