Though her dress style is reminiscently Gothic in appearance, she has, oddly enough, never established to be an actual []. This was even stated by [Vasquez] himself. Coincidentally, Gaz's clothing style bears a strong resemblance to that of Pepito the Antichrist (the son of Satan and a Christian woman), another creation of Jhonen's). Around Gaz's neck is a necklace in the shape of a stylized human skull. When she was younger, she still wore a black dress but had a bow in her hair, so it's unknown how or when she acquired her necklace. Pepito wears similar clothing and jewelry, only his shoes are boots and his necklace is in the shape of a lock (though Gaz appears to be wearing boots in a scene of []).
The most unique characteristics about Gaz are her hair and eyes. Her purple hair is cubic and fashioned into five spikes, and takes on the ominous appearance of a mouth with fangs (actually a stylized [cut]). Also, her eyes are almost always closed or squinting, but when they are open her eyes are an amber color. In the [], her eyes are blue with the exception of being brown/amber in one scene. She opens her eyes when she is surprised, enraptured or really angry (she opens one eye occasionally when she makes a point).
In season two of the show, Gaz's head was remodeled to be more angular, like her brother's head, when facing forward towards the camera, rather than having a round shape (though she had the rounder shape when she was younger and in the non-canon video game [MLB], where [] is her partner). Her head seems to be large compared to normal human beings, but she accuses Dib (like almost every character) of having a big head. As the series goes on, she gets taller, and even has some facial changes, but her voice doesn't change much.
Gaz is best known for her anti-social and dark nature, along with her obsession with pizza and video games. When she isn't eating pizza or playing her [Slave], Gaz typically just beats on Dib because of his talking (which enrages her) and appears to enjoy doing so. Although she is almost always grouchy and unhappy, her few interests have been known to coax a more positive side out of her, and in [] she was friendly to the security guards at her father's television studio and said to her brother in a relatively cheery tone, "I thought I'd help you out", even after swearing revenge on her brother for stealing the last pizza slice.
Gaz, like most modern children, loves to play video games on her Game Slave, and has an obsession with Poop Cola and []. If anyone comes between herself and one of these things, she has a tendency to vow revenge, and make things very unpleasant for them. A prime example for this was seen in the episode [Slave 2], in which a hyperactive boy called [] took the last Game Slave 2 in stock at [mall], and Gaz stalked and terrorized Iggins until he surrendered the Game Slave 2 to her.
Gaz is the only one, with the exception of Dib, to realize that [] is really an alien. In [Pizza Hog], she replied to Dib's comment that Zim was trying to enslave all mankind with "but he's so bad at it". Another example was seen in [Taster of Pork], where she acknowledged Zim's an alien and said that "he's too dumb to take over the world". In-between the events of the first few episodes, she and Zim met, though it was one that was far from friendly.
Although she usually plays only a supporting role as the unwilling sidekick to Dib, her obsessive-compulsive brother, she has been the main subject in three episodes:
- In [Slave 2], Gaz attempted to buy the Game Slave 2 handheld device, and ruthlessly terrorized a kid named [] when he made off with the last one in stock.
- In [Pizza Hog], she proved that she will do anything to eat out at [], even rescuing her brother from Zim's clutches.
- In [Taster of Pork], the episode chronicled the events that ensued when a mishap with one of Dib's spelldrives caused her to be cursed to a fate of tasting nothing but pork.
Throughout the show, it is demonstrated, but never actually said, that Gaz has amazing powers. Her powers includes: the ability to fix, pilot, manipulate, and in general control anything electronic, the ability to get any place she needs, the demonic ability to levitate on pure rage alone, to create fires at will, to generate spookiness in a tangible manner, etc. She is also shown to be capable of using [] technology and her piloting skills seem to be on par, if not greater than Zim's, as she was able to pilot one of his ships with ease.
It is possible that these abilities, being completely unnatural, are actually a result of her being a genetic experiment of Professor Membrane, just as it is rumored that her brother is. She, despite her demonic nature, has a sort of connection to the holy, as shown in [Slave 2], when upon getting her game back, the stormy night turned to a bright sunny day, and her hair returned to its natural shape. She also commented on how "the rightful order has been restored". In [of Doom], she similarly stated, "All is right with the world again". These were obvious references to horror movies such as The Ring and The Grudge, which also contained considerably creepy girls, as well as the plot of Game Slave 2, which somewhat parodied the aforementioned movies. Additionally, an immediate change of atmosphere occurs when the girl gets really angry.
- Her voice actress, Melissa Fahn, has stated in the commentary for [Most Horrible X-Mas Ever] that Gaz actually can show positive emotions and love others; she just has a big ego (much like Zim) and thinks she is better than everyone else, hence her rotten attitude and demeanor around everyone she makes contact with throughout the series. Melissa also confirmed in the same commentary that Gaz is the smartest character, even more intelligent than [own father], agreeing with Jhonen.
- In the episode [Harvest], Gaz claimed to have a []. Her comment is most likely a retort to Dib's comment about Zim's Squeedly-Spooch.
- The following episodes in which Gaz smiled were [Teacher Night] (while snickering at Zim and Dib's misfortunes), [Wettening] (before dropping her water balloon on Dib after Zim's watery victory against him), and [Taster of Pork] (while she attempted to torture Dib with her [toys], and mentioned that she had programmed them to feed on human flesh). She also smiled several times in the [], but, given the many differences and inconsistencies seen in the "episode", its canonicity is called into question.
- Her demonic nature, misanthropic demeanor and constant abuse of [brother] have caused controversy from [] and the magazine [Parenting Today]; even some of her darkest lines in episodes like NanoZIM, Gaz, Taster of Pork and [Slave 2] have been called into question by Christians due to the negativity of her statements. However, Jhonen has not made any comment on the controversy as of late, nor has Melissa.
- Ironically, Fahn previously voiced the eponymous character in the Hello Kitty Paradise animated series, and has a very pleasant demeanor.
- Gaz's full first name is [], a play on the word gasoline, but was never mentioned in the series. The play on words fits her personality rather well: Like gasoline when ignited, Gaz has a very fiery temper when provoked.
- Her eyes are brown/hazel, although they were supposed to be light blue as they were in the Pilot. A coloring error led to her current eye color of amber/hazel.
- In an image on Nicktoons's official site, Gaz is seen sitting playing her [Slave] 2 in Zim and Dib's classroom in front of [Bitters], who is growling at her. However, [Teacher Night] and [Taster of Pork] notably explain that she is in [Elliot]'s class.
- During the Intro, Gaz breaks the fourth wall by putting her hand on the screen and brusquely shoving it aside.
- Gaz was seen in two of Snafu's webcomics: PowerPuff Girls Doujinshi(as a cameo) and Invader Zim: Manifest Doom, where she was one of the main characters.
- In a very sketchy plot idea for the nonexistent series finale put forth by head writer Eric Trueheart, Gaz was going to align herself with the Irkens. She would have encouraged Zim to continue fighting in his vision of seeing his own people dying (hiding her identity in a cloak and hood until the time is right, with only her eyes visible in the shadows), and afterwards she would team up with him to put an end to the fighting. After Zim is declared the next Tallest, she would move to Irk with Zim and join him in ruling the planet as his consort, with Zim having completely lost the desire to destroy the Earth after realizing there is beauty in Earth life. However, this was only one of many sketchy plot ideas for this episode, and, coupled with the fact that it is at odds with many key points established in the series, this particular idea should not be considered the official canonical one.
- Gaz is a playable character in [MLB] alongside [], though the two don't seem to interact during gameplay. Best used as a pitcher, her throw is one of the fastest in the entire game; her throw leaves a trail of skulls in the same designs as the ones from her part in the show's intro scene. Her clothes are the same as in the show, only her dress has pinstripes and she wears a red baseball cap that transforms into a first baseman's helmet when she is at first base. In [concept sketches by Aaron Alexovich], in the series she was going to actually wear a helmet that would cover her hair. Additionally, she also has a collectible card; it mentions her complaining that the whole idea is as bad as a 2-bit arcade game.
- Gazlene is a character that can be rescued in Nicktoons: Globs of Doom, with [Fahn] providing her voice as usual. When you rescue her, she actually congratulates you for rescuing her.
- The word "gaz" is also the name of a type of candy found in the Middle East. The word, translated from Farsi, means "sap".
- In [Most Horrible X-Mas Ever], Gaz's anger and hatred is revealed by [Vasquez] to be able to fix the ship. This seems to suggest that Irken ships can be fixed faster by simply feeling a lot of emotion, or to express that Gaz is much smarter then Dib in some ways.