|“||It's as only as real as you let it be.||”|
Zimmy is a mysterious student at Gunnerkrigg Court with reality warping abilities. Her given name is Zeta, but she dislikes the name.  She has a very close relationship with Gamma Czarnecki – the two of them are a couple.
Zimmy is a thin girl with grey tinted skin, long black hair and pointed teeth. Her most striking feature is the black gunk that usually covers her eyes, which Tom has said is a sort of "visual metaphor[sic]". Notably, the black mess covering her eyes on dissipates whenever Zimmy stands in the rain, revealing two scarlet red eyes underneath. Zimmy doesn't seem to really care about her physical appearance. Her hair is tangled and messy, her school uniform is usually in disarray and she doesn't take showers as much as she should. She is usually seen frowning or grinning mischievously.
She has a generally grumpy attitude, displaying a short temper and a general disdain for those around her, with the notable exception of Gamma, and later on, Antimony Carver as well. In general she tends to avoid other people, and doesn't like to be watched. The horrific hallucinations she experiences daily due to her abilities have left her paranoid and prone to mood swings. She has also been shown to have a mischievous, if somewhat dark, sense of humour. She speaks with a broken Birmingham accent and has a tendency to swear more than the other characters.
Zimmy has displayed the ability, both willingly and unwillingly, to project the conscious and subconscious thoughts of herself and others into a form that can be seen and interacted with by others. She experiences these abilities as frequent horrific hallucinations. Consequently, she views her abilities as a curse. As part of her hallucinations, she sometimes ends up in a Birmingham-like city populated by faceless people. Unfortunately, she cannot tell these people apart from real ones, as even the real ones look faceless to her.
The only person who can quell these hallucinations is Gamma, as they disappear when she's near Zimmy (although Annie has a similar effect, if somewhat less effective) and for her to utilize her abilities, Gamma must not be present. However, the often macabre freakish nature of these powerful projections mean that they are capable of being incredibly dangerous when Gamma is not alleviating them, hence her constant companionship with Zimmy. Apparently Zimmy never sleeps, which makes it difficult for Gamma, who can only suppress Zimmy's hallucinations while awake.
During storms, Zimmy runs outside and lets the rain wash over her. It has an odd effect: her body sizzles and actually releases rivulets of steam, and the gunk on her eyes is completely washed away, revealing her red eyes. 
However rain released back into the skies from the Power Station doesn't work, since it is after the station has taken away the water's natural source of etheric energy.  Standing in the rain is the only time when Zimmy is at least a little happy, as it temporarily alleviates the hallucinations that constantly plague her. During this short period, Zimmy displays a degree of playfulness and rationality that is not often seen from her.
Zimmy's abilities also extend to detecting to etheric connections, communicating telepathically (only seen with Gamma), entering a room undetected, hearing thoughts (seen briefly with Kat) and manipulating memories., , ,
Zimmy was born with her powers. She once had parents, but apparently left them to live on the streets. Tom has stated that they don't remember who she is and if they could, they would be glad that she left.
Nearly one and a half year (one year and 102 days) before Chapter 11: Dobranoc, Gamma she was for some reason sad and alone in the streets of Birmingham. That day, she met Gamma Czarnecki for the first time. 76 days later they see a creature that looks somewhat like a Rogat Orjak. She and Gamma live together for some time, sometimes sneaking into and occasionally meeting up in a toy store whenever they were separated.
After months of seemingly living on the streets , two employees of The Court comes and offer them both to attend the Court, but with freedom to go where they please, when they please. The two of them accept.
On The Court
When Zimmy is first seen in the court she and Gamma are participating in a science fair with an experiment that has not been revealed yet.
Later, Zimmy and Gamma come to Annie for help. Gamma can only chase away Zimmy's hallucinations while she's awake, but she's very tired, and they need Annie to stay with Zimmy while Gamma rests. Apparently Annie's abilities have a similar, albeit weaker, effect on Zimmy as Gamma's.
Just before a storm breaks out the three goes outside. When it starts raining the drops boils on Zimmy's head, resulting in her becoming very playful and a lot better mood and the black gunk around her eyes disappears.
The duo later comes up to the roofs of a building around The Power Station because it messes with Zimmy's head. There are other kids there, which they at first think are projections of Zimmy's mind. As they stand on the rooftop the station starts some sort of procedure where it drains the water in order to form clouds and then sends off an electrical charge into the horizon. Zimmy gets very disappointed when she realizes the rain doesn't have the same effect as it had before, her frustration builds up and she ends up in Zimmyngham with Gamma, Annie and Jack Hyland. Eventually Zimmy, Gamma and Annie gets out without damage, although, one of Zimmy's Whitelegs attach itself to Jack.
In her next appearance she seems to have some sort of hallucination, thinking that she's Annie walking around in Zimmyngham. When she sees how close Gamma gets to Annie, whom she thinks is herself, she snaps and remembers that she is in fact Zimmy. It then starts raining and they are all taken out of Zimmyngham, this time the rain does have the positive effect on Zimmy's mind and mood, as seen before.Zimmy grabs the Whiteleg-spider on Jack's head and squashes it.
Later she is seen running through a dark alley presumably in Zimmyngham to avoid Gamma as Gamma is trying to have her go help Annie which is currently in the court hospital. She's eventually convinced. When she's there, her and Gamma split up, which lets her wild mind flow more. She goes into Annie's dreams and eventually sends a message to her father, by mentally punching him. After this she is brought back to the hospital room, but finds that she's still inside some sort of dream. When she wakes up she panics at the sight of Kat, Gamma is brought back in and then she and Gamma somehow disappear.
She and Gamma share an unexplained telepathic connection, and they communicate to each other solely through this way. As a result, she and Gamma have developed an extremely close relationship, to the point where Annie has referred to the pair as an "item". Zimmy herself has said that she loves Gamma and wouldn't be alive it it weren't for her. Zimmy's love for Gamma has shown to be somewhat possessive, as seen when she translated what the students said to Gamma as insults and flew into a rage when the Antimony (as Zimmy) got too close to Gamma in Zimmyngham.  
Zimmy is cautiously indifferent about her. She sees that Antimony doesn't give her too much trouble and even helped her and Gamma a couple times, so she tolerates her.  She usually calls her "Carver" rather than Antimony or Annie.
Zimmy knows Jones, and Jones knows Zimmy well enough to know the extent of her powers as well as her personality.
See Word of Tom: Zimmy and Gamma for more.
- Zimmy's true name Zeta, is taken from the eponymous sixth letter of the Greek alphabet, it is also the Latin letter Z in English. The lowercase version of Zeta is ζ.
- Zimmy and Gamma are one of the oldest characters in the story, Tom came up with them years before writing Gunnerkrigg Court and they were originally supposed to be characters in a scrapped comic called Alphabet Soup.
- Zimmy's theme song is "Stress" by Justice.
- Tom has stated Zimmy's abilities are at least partly inspired by the effects of panic attacks.