At around 2027, the young Gunther Hermann is described as a man in his twenties, with blonde hair, ice-blue eyes, a thick neck and the physique of a body-builder. At this time, his only visible augmentation is his left hand.
Previously, during the early 2020s, Gunther served in the German counter-terrorist unit GSG 9 but he was not satisfied by the way they worked. After getting into trouble, he was contacted by the Tyrants, who offered to make his problems go away in return for his services.
During his time with the Tyrants, Hermann is involved in many of their assassinations, including the assassination of Garrett Dansky, chief executive of Caidin Global. During that mission, he murders Matt Ryan, Anna Kelso's superior and close friend.
During one of the Tyrants' major operations, Gunther, Saxon, and Scott Hardesty are sent to kill Mikhail Kontarsky, an administrator of the Russian committee on Human Augmentation, in the Hotel Novoe Rostov in Moscow. They find Kontarsky in a secret room, speaking to a mysterious figure, "Janus." Saxon hesitates, and Hardesty kills Kontarsky from a sniper perch across the street.
Later, Gunther and Saxon are both tased and knocked out onboard the Tyrant Jetliner. When they awake, Jaron explains that one of the two is not loyal to the group, and the two must fight to the death to determine which. He throws a handgun with a single round, and the two fight over it. Saxon eventually gets the pistol, but he refuses to kill Gunther. Jaron says that the fight was just a test between the two, and that the round is a blank. Afterwards, he, Saxon, and Hardesty are sent in Virginia to kill Ronald Temple and anyone currently in his house.
When Saxon decides to defect from the Tyrants and escape the Tyrant Jetliner, Gunther confronts Saxon for another fight onboard a Tyrant plane. Saxon shoots Gunther in the eye with a taser slug and breaks several bones in his torso, physically scarring him. Saxon eventually escapes from the jetliner. Gunther uses an adhesive patch to cover his ruined eye, but shows no signs of suffering for the injury.
The Tyrants' next mission is in Geneva, Switzerland, where they plan to assassinate William Taggart of Humanity Front on the steps of the Palais de Nations, making him a martyr for the anti-augmentation cause and push for a vote on UN regulation. Gunther is driving a van loaded with a truck bomb when Anna, riding in a nearby vehicle, recognizes him as Matt Ryan's killer. After damaging Gunther's van with gunfire, Anna jumps onto his van and fires into the driver-side window. Gunther attempts to return fire but his shots are wide. Anna then hits Gunther in the head with a shot that carves across Gunther's skull. The impact of the shot causes Gunther to lose control of the van, which swerves and throws Anna off. The van plummets into the Rhône River and the truck bomb detonates.
Gunther is recovered from the Rhône River by Majestic 12 operatives. Gunther has been heavily crippled and scarred by the explosion. However, Bob Page, leader of MJ12, proceeds to extensively reconstruct Gunther using cybernetic augmentations so that he could be redeployed at a later time.
|"He was almost a full-body prosthesis cyborg and what flesh there was of him seemed more like a coating applied to a steel sculpture than the true matter of the man. In particular, his organic face hung on a hairless chromed head like a mask, inset with two bulky crimson optic implants that gave him a permanently doleful expression."|
|- description of Gunther Hermann, Deus Ex: Black Light|
Gunther and his team easily and ruthlessly dispatch the TF29 personnel on the train, but their operation is interrupted by the arrival of Adam Jensen. Thorne orders Gunther to attack and kill Jensen, but Gunther rebukes her, saying that killing Jensen is contrary to the original orders. Gunther nonetheless complies and pursues Jensen, who had fled to another part of the train. Gunther's ceramic-metallic armor proves effective in deflecting Jensen's monomolecular blades. Although Jensen is able to damage Gunther's eye augmentation, Gunther gains the upper hand by breaking Jensen's armor and ribs with a single punch to the chest and then throwing Jensen against the wall. However, Jensen manages to destroy the train's control panel, turning the train into a runaway. Jensen taunts Gunther and tells him that if they continue fighting, they will both die when the train crashes. Without hesitation, Gunther escapes the train.
|"He's not the most intelligent agent in UNATCO, but he's cunning, strong and steadfast. Gunther has given his loyalty to UNATCO and those he considers to have proven themselves worthy of respect. That does not apply, by the way, to any wet-behind-the-ears kid with a cool sense of fashion and no scars — i.e., you.
Gunther recognizes that the world is divided into the strong and the weak. The strong make the rules; the strong enforce them. He is not concerned overmuch with right and wrong, and in fact considers the concept unrealistic. He's given his allegiance irrevocably to UNATCO in return for power: both having his personal strength augmented and being a member of a world-changing organization. His loyalty to Anna Navarre borders on the dog-like. He holds no regard for death, either his own or others. The only thing he truly fears is that his augmentations may become outdated, rendering him weak and unable to perform his duties."
|- description of Gunther Hermann, Deus Ex|
Hermann apparently has self-esteem issues; an overheard conversation between Gunther and Anna Navarre reveals that his large fingers may also hinder his ability to operate soda machines, although he insists that the "maintenance man" switched the cans of orange soda in the machine with lemon-lime, as "he knows I like orange." His augmented fingers may also cause him considerable difficulty performing other common tasks such as typing, as his consistently misspelled emails generally either have missing letters or contain additional letters that are adjacent to the intended letter on a standard QWERTY keyboard. An e-mail from Jaime Reyes quoting an anonymous e-mail from a mech-aug (clearly Gunther, judging from the spelling) in which he expresses concern that he and those like him "well be sld at flee markets... old gray golems for scareing the children".
Gunther often finds himself fantasizing about ever more impractical augmentations he believes his superiors might offer him, such as a head-mounted gun, or "skul-gun," that would allow him to kill without using his arms. According to Gunther, the maintenance men in UNATCO HQ intentionally swap the orange soda's for lemon-lime ones in the vending machine. Anna suggests that his hand might have slipped, but he rejects this theory. In actuality, Gunther was indeed a victim of conspiracy by the maintenance men.
Gunther takes over from JC Denton once he has destroyed the NSF generator in the Warehouse District, New York City. Soon after this, he is deployed to LaGuardia Airport to oversee the UNATCO peacekeeping occupation. Afterwards, he can be found near the entrance to the Battery Park subway station, if JC gets that far after UNATCO raids the 'Ton Hotel. Once JC has defected from UNATCO, Gunther is sent to kill him, whom he engages in Cathedrale de Payens, Paris.
In the cathedral, an MJ12 trooper's journal reveals that Hermann had been passionately awaiting JC for a while and that the trooper thought he heard him cry once.
JC Denton's first real encounter with Gunther, apart from the training course, is optionally rescuing him from the NSF terrorists at the base of the Statue of Liberty. Whether JC does this (and whether he arms Gunther, or makes him run back to base unarmed) sets the stage for how Gunther feels about him later on.
At the Cathedrale de Payens, if the Gunther's killphrase has been discovered, JC Denton is given the choice between calling out the killphrase or attempting to reason with him. If Gunther is killed, Walton Simons informs JC that he only sent Gunther because he was tired of him complaining about wanting to avenge Anna Navarre and wanting a tune-up.
- Gunther is supposed to be killed at the cathedral. While it's hypothetically possible to go around him, the game treats him as dead after Paris.
- JC can completely avoid seeing Gunther in person until Paris, except for listening his Infolink messages. JC can also avoid speaking to him for all the game.
- Gunther has 400 health (head: 600 health). Prior to the meeting at the cathedral, Gunther is invincible.
- When no longer invincible, Gunther takes full damage against shot damage, sabot damage, and explosion damage, and 10% damage against gas damage, poison damage, radiation damage, and shock damage.
- Gunther is immune to all other damage types, including stun damage (inflicted by the riot prod), knockout damage (inflicted by the baton), flame damage, and burn damage.
- Gunther's speech is slurred, but it is never revealed in the game if this is due to a speech impediment or to him not completely learning English. Though we never hear him speak German at length, if you later attack him on the roof of the compound housing the destroyed power generator -- in the third mission -- he will say "Mein Gott!" In the cathedral in Paris, if you manage to resist his attacks for a long time, he will eventually exclaim "Unglaublich!" which is German for "Unbelievable!"
- Gunther's killphrase is Laputan machine. Uttering the phrase in Gunther's presence discharges a 400 milliamp electric current into his midbrain. The phrase itself refers to the flying city of Laputa from Jonathan Swift's Gulliver's Travels. In the novel, the Laputans are masters of theoretical engineering but completely lacking in practical mechanical knowledge; the devices they produce are tremendously innovative "on paper" but badly flawed in practice (like Gunther himself).
- In the concept art, Gunther Hermann appeared to be significantly less mechanically augmented, but he was dramatically changed before the final version of the game.
- In the concept art, Gunther highly resembles Rutger Hauer's character, Roy Batty, from the 1982 film Blade Runner. Both characters have a moral dilemma addressing their humanity.
- In Invisible War, a couple of homeless are raiding the old UNATCO break room and discover that the orange selection of the vending machine was indeed stocked with lemon-lime instead. One of their theories was that it was due to "office politics" with someone trying to get back at someone else. This is in line with Gunther's claim that the maintenance men purposefully swapped the drink selection to prank him.
- While the "Skull Gun" concept was first introduced in Deus Ex, an e-mail on David Sarif's computer in Deus Ex: Human Revolution discusses the concept as well, making the 'Skull Gun' idea date back to at least 2027.
- This is further evidenced in Deus Ex: The Fall, in an e-mail Gunther sent Namir telling him he is getting his augs redone and maybe he will get that skull gun aug he's been wanting, suggesting the Tyrants may have access to such early stage nano-augmentation, or at least have experimented with making a Skull Gun as a mechanical aug.
- In Deus Ex: Invisible War, it is revealed that UNATCO received a shipment of Skull Guns shortly after Hermann's demise.
- The Skull Gun idea was first introduced by Neal Stephenson in his book The Diamond Age, in which a character called Bud has a 'Skull Gun' implanted in his forehead. The skull gun uses nanotechnology to launch small but lethal projectiles from a concealed hole in the user's forehead. The weapon also comes with a voice-operated firing system and a variety of deadly ammunition like Cripplers, Hellfires and Electrostun rounds.
- "That will be adequate."
- "No. I wanted orange. It gave me lemon-lime."
- "I do not make mistakes of that kind."
- "I want to be the one to execute Lebedev."
- "Again they ignore me. Again they think they have a better punishment for a traitor than a shotgun to the head."
- "No, I cannot forgive. No... not the killing of Agent Navarre. I will follow you. Denton, I will get you!"
- "I see you, a thief on the roof. My new satellite link has both infrared and the x-ray spectrum. I see your heart beating. I see you are afraid."
- "You are a small, prowling mouse. And dumb like a mouse. You keep coming, like you forget about Agent Navarre. I remember Agent Navarre. I remember for everyone."
- "Manderley has assigned me the peacekeeping occupation of this district."
- "I-I-am not a machin-"
- "THAT is a gentlemen's agreement."
- "Agent, open the door!"
- "I believe I will enjoy this."
- "Unglaublich!" (Unbelievable in German)
- "If you stay here you will be bored!"
- "Advance up the stairs to the command center at the top. I will take my rusty metal bones and sweep away into the junk pile."