Greybane is a male mutant. He is characterized by a scar across his face, a bushy gray beard, extremely keen hearing and the brown cloak that partially hides his face.
Learning of Greybane's abilities, Geoffrey aimed to help enhance other soldiers with his genes. However before he could complete his aims the zombie virus engulfed much of mankind. In an attempt to counter the zombies, Geoffrey attempted to modify Greybane (and Bug's) genes, though he merely mutated the pair.
Upon waking up after the surgery Greybane discovered a dying Geoffrey (who had been attacked by Bug). Promising to keep Geoffrey alive, Greybane injected him with the zombie virus before chaining him up in the basement of a house just outside of New Hammerston. Greybane then began to hunt Bug, looking to avenge his friend.
Greybane first meets the main characters outside of Rosa's Cantina in Allergies. He reveals to the group that he heard all of their discussion, though swears that he won't say anything of it. He also says that he'll keep a watch out for them in future.
Greybane returns in Unknown Hero where he saves the survivors from the zombies. While trying to convince them to trust him, Bug arrives. Greybane subdues him, but is injured in the process. Although still cautious of him the survivors rescue him and take him to an abandoned house.
While resting at the house Jan is killed by Rosa. Upon waking Greybane realises a vampire has been near and heads out, where he finds Rusty. Rusty, fuming over Jan's death, attacks Greybane, though is easily subdued. Greybane calms him down and, when Annika arrives, explains the situation to her.
Rusty, although originally intending to simply leave the group, asks Greybane instead to take them to New Hammerston.
While on their way to the colony the group takes rest in an abandoned building, Greybane senses a vampire nearby. Intending to finish the vampire Greybane heads out and is about to deal the fatal blow, when he discovers it is Rosa, whom he recognises from New Hammerston. While he still intends to kill her, he is interrupted by the arrival of Joe, Bernie and Scrufflebeck.
In the commotion Rosa flees, though is shot on her way out by Bug. Realising his nemesis is nearby Greybane heads out, intending to at last finish their feud. The two fight, and while Greybane comes out the victor, they are captured by machines before he can finish Bug.
While on their way to Machine City the machine detects Greybane's body mass increasing, though sedates him.
After being brought to Machine City Greybane is analysed by the machines and discovered to be a new mutation. Although the machines plan to perform a vivisection on him, he transforms into his alternative form, overcoming the machine's sedative and breaking out. He then proceeds to destroy the machine building.
While rampaging he is sensed by Samuel, who, bringing him to the central area, attempts to control his mind. Before he can be assimilated however the link is severed (due to Inner Joe's attack on Samuel) and Greybane, now free, manages to attack and destroy the central instillation.
Greybane then takes Samuel's brain in a jar and leaves the building, coming across Nick and Scrufflebeck on his way out. The doctor, startled by Greybane's appearance nonetheless agrees to go with him back to New Hammerston. Letting the doctor go a little ahead Greybane tells Bug (who is believed to have died in the building) to rest in hell.
Heading back to New Hammerston the trio take shelter in an abandoned building. While there Greybane and Nick discuss the nature of the Plant Monsters, the former stating he feels they will one day take over the world completely. After this Nick asks him about the jar, Greybane explains it's a brain and says to leave it at that, then telling Nick to get some rest, as the next day they'll be back at the colony.
Greybane arrives in Zomgack, where he prevents Annika from killing Geoffrey. He then explains his history to the group, before suggesting they head back to the colony.
Following the screams, Greybane arrives to find Karen and her grandfather Dwight facing off Gwenn and her Dragoons. Though Greybane scares them off (injuring a Dragoon in the process) he is unable to stop Gwenn from killing Dwight.
Upon the arrival of Nick, Greybane suggests the group take shelter, where he is told something of Karen's history.
Later Greybane, Nick and Karen are shown burying Dwight. After this Greybane announces that he intends to return the pair to New Hammerston, before he goes to deal with the Dragoons. Both Nick and Karen refuse however, and Greybane eventually agrees to take them with him.
On the way to Limeridge Greybane leaves the other two to gather supplies. Upon returning he discovers that the Dragoon has fled with their previous supplies. Greybane then decides to head to the port of Brookfield.
Greybane is shown to be a rather withdrawn character. He speaks little and seems to prefer his own company. Despite this he does seem to be a caring figure, looking out for a number of other survivors (being especially caring towards Nathan).
Despite making for quite a fearsome character, he seems to get on well with those whom he comes across, even if he can seem distant. While he gets on with most humans he seems to despise most other races, most notably vampires.
Although Greybane and Bug don't appear to have been close, the pair would have known each other prior to Geoffrey's experiments.
The two seem to have once been very close. While Geoffrey seems to have seen Greybane as the solution to many of man's problem, he also seems to have respected his friendship.
Even as a human Greybane was notably powerful, having strength and speed beyond that of a normal person.
Following Geoffrey's operation Greybane seems to have gained a number of additional, more unnatural powers: the ability to heal quickly, super sensitive hearing and claws.
On top of this he seems to be able to transform into some sort of monster form, his body mass and strength increasing with it. While in this form he appears to be even stronger, having the ability to overcome the machine's sedative and escape from their capture.