Zim

While most Irkens are expected to be ruthlessly loyal to the Empire, Zim is considered overzealous even by their standards: Brash, arrogant, and overconfident, Zim's tendency to cause wanton destruction makes him a danger to himself and his own people, yet he still considers himself a mighty Irken warrior. In addition, he is acutely narcissistic and megalomaniacal, congratulating himself on even the smallest of successes; these, however, are few and far between. However, the pride he feels for his planet and its culture, as well as its people, is to be admired.

Despite his self-proclaimed greatness, Zim rarely succeeds in his attempts and is sadly held up as a complete laughingstock, a scapegoat, or a figure of contempt by his own species, a fact that he is either oblivious to, knows about but keeps a brave face, or simply chooses not to notice; this is hinted at by the fact that due to his self-absorbed nature, it prevents Zim from seeing his failures, past and present. He claims to be proud of all the past disasters he has caused (as revealed in "The Nightmare Begins" and in the unproduced episode "The Trial", and rarely acknowledges his defeats in his present mission on Earth (often blaming them on other characters like other supervillains do, or other factors, or completely changing the subject).

Zim’s destructive nature.

When he is told by Tak in "Tak: The Hideous New Girl" that his "mission" was really an attempt to get rid of him, he simply rejects her statement as a lie. It is not entirely clear whether Zim is aware of his failings in the eyes of his leaders and is desperately trying to compensate for them, or whether he really is just completely oblivious to the opinions of others, as he had deluded himself into thinking he's "amazing" and can do no wrong.

Despite this, Zim is innocently loyal and obedient to the Tallest, the Irken Empire, his planet and his people, and is willing to go to ridiculous lengths to please his leaders, to the point that he is zealously willing to endure pain or hardship in order to gain their respect. In the episode "Planet Jackers", Zim even undergoes a rather severe beating in the name of protecting his mission and for the sake of Irken benefit.

Interestingly despite the fact that Zim has both a strong hatred for humanity and is a well known defective he refuses to abandon his post on Earth as seen in “The Frycook What Came from All That Space” where his main concern was to escape the restaurant in which he was being held captive by Sizz-Lorr so he could return to his “secret mission”, this is most likely because he’s under the belief that he’s still an Invader and had a mission to fulfill while he only saw his initial exile on Foodcourtia first as “vacation” that he claimed didn’t need and later as a horrible experience that kept him away from conquering his "assigned planet” and after he escaped a second time, Zim happily returned to Earth, eager to continue his mission and was even relieved to be “home”.

Zim and GIR exercising in Invader Zim: Enter the Florpus

Zim's laugh and mannerisms are overly theatrical, which is fitting for his dramatic personality. As seen in "Future Dib" and "Bolognius Maximus", he can let his maniacal laugh linger for too long and be unaware of the disturbance he causes.

By turns this would-be Invader can be petulant, critical, paranoid, humorous, sarcastic, pretentious, pedantic, depressive, melodramatic, and even occasionally whimsical. He is often curiously attached to random objects, such as his robot bee ("Tak: The Hideous New Girl") or Li'l Meat Man. He is immensely proud of anything he creates, yet is often frustrated when his devices fail to live up to his grandiose expectations.

Zim’s lack of foresight backfired.

It's clear that Zim is highly intelligent (in his own crafty sort of way) and is a keen manipulator of tools and devices, but has absolutely no apparent interest in thinking things through to their logical conclusion. The fact that creating and unleashing a giant water balloon on the city from orbit in "The Wettening" will also destroy his house (but not his base) doesn't seem to enter his mind.

When he hijacks the Massive in "Backseat Drivers from Beyond the Stars" he only considers (incorrectly) that the Tallest will be appreciative of his efforts. Nor does he really consider the consequence of restoring the natural time-flow of a city-leveling explosion in "Walk For Your Lives", despite being warned several times, by GIR no less, until his base was coming down around him. An alternative explanation is that he is aware of the consequences of his actions, but believes that they are worth reaching his goals and is willing to amend them after he does so.

Zim clearly is more than capable of destroying or conquering Earth, but he hardly ever uses this capability correctly. For instance, when he is accidentally sent a Megadoomer robot, he decides to use it to kill Dib, when the robot obviously has the destructive power to do better things, although the fact that Zim admits that the idea was "a bit much", suggests some self awareness on his part, this very moment also seems to hint that he has no qualms in killing his human enemy in the most horrible way imaginable.

Zim evilly using rubber piggies to get rid of Dib.

Unsurprisingly this has been previously shown to be the case as in "Bad, Bad Rubber Piggy", Zim used a Temporal Object Displacement Device in order to torture Dib with rubber piggies with the ultimate goal of eliminating him over an extended period of time, the fact that Zim decided to kill Dib over several years rather a quick demise implies a sadistic side as it was seen that Zim enjoyed the outcome each time.

Curiously when Zim briefly believed he succeeded, he didn't laugh manically or claim a loud victory like one would expect from him but instead celebrated with a drink and dismissively called Dib a "Foolish Earth creature", this could be because in Zim's eyes, Dib is nothing more than an annoyance that keeps him from completing his mission and as a result Zim may have viewed the human's temporary death as an insignificant thing rather than the passing of a worthy opponent.

Zim freaking out.

Despite his many failures since his mission began, it shouldn't be overlooked that Zim has often come very close to taking over the planet, only to be thwarted by Dib or Gaz, or even his own negligence, Jhonen Vasquez has gone on record by saying that Zim has a "horrible sense of direction" and he is so preoccupied with unimportant "threats" that he doesn't get anything done, this may be a result of his paranoia.

One of Zim's abilities is his somewhat inconsistent skills at piloting; while in a tense situation he flies masterfully but seems to crash on most other occasions, and his skills pale in comparison to opponents adept at hand-eye coordination or overall agility (such as Gaz). Zim also has admirable engineering ability; in "Walk of Doom" he singlehandedly improved the SIR Unit guidance system chip, and in "Walk for Your Lives" he hand-built a variable time stasis field capable of altering individual time-fields. He is immensely proud of anything he creates, yet is often frustrated when his devices fail to live up to his grandiose expectations.

Zim calling GIR to rescue him from being “captured”.

Even though Zim often affirms that he wishes to conquer Earth, it has been hinted that he would not actually want to rule the planet himself, it has also been suggested that he prefers simply to do his job as an Invader rather than becoming master of the inhabitants he wants to conquer or destroy.

For example in "Attack of the Saucer Morons", Zim gained a group of human worshippers who would be willing to do his bidding, Zim, however, panics and tries to escape from them, believing that they are trying to capture him for dissection and study. In the Nickelodeon Magazine Special, in which Zim somehow finally takes over the world in a ridiculous short amount of time, and while he claimed to now love Earth because he’s the one in control, he doesn't stay to rule for very long, instead leaving the planet forever (along with Dib, GIR, and Minimoose) to ride alien bunny rabbits and drink soda.

Zim shows no remorse for the people that are harmed due to his actions and almost never takes responsibility for his mistakes, priding himself on causing destruction in the name of the Irken Empire, even when said destruction is aimed towards other Irkens. However, he has been shown of being capable of forming temporary alliances with others, such as Gaz in both Issue 16 of the comics and in the cancelled episode "Ten Minutes to Doom". In the former, by agreeing to take Gaz to Arcadikon, it is shown that he understands her wants and values her interests, showing a level of understanding with her.

Zim with his squad that he’ll callously use as cannon fodder.

More or less he considers everyone else but himself (even members of his own race) expendable for his own plans, often exploiting them to reach his own goals with apparent disregard for their safety or well-being. For example, in "Hobo 13", Zim sends the soldiers under his command to their dooms when other, safer methods could be taken (even using Throbulator, the last soldier in his unit, as a battering ram), causing Sergeant Hobo 678 to fail him automatically despite the fact that Zim manages to survive the obstacle course.

Another example is when Zim destroys a candy machine in "Tak: The Hideous New Girl", ending Tak's goal of becoming an Invader and he either doesn't realize that she's trapped or, more likely, he doesn't care. His behavior and unawareness of his actions are most likely the result of him being Defective, as revealed in the cancelled episode "The Trial".

At the moment, Zim is most comfortable in ensuring destruction rather than gaining power and when he does gain power, he seems not to care much for it, treating it more like a means to an end since it has been heavily implied that he only seeks to take control of the planet to mainly earn the praise and respect of his leaders. An example of this was seen in "The Most Horrible X-Mas Ever", where he easily got the entire human race to worship him when he disguised himself as Santa Claus, but rather than to build an empire for himself, he cared more about sending the humans away to the Tallest and thus, their own doom. Towards the end of Enter the Florpus, Zim grows bored of the humans' panicking at the Florpus Hole, saying "why don't you bow down before me or something?"

Smeet Zim hugging the "cold, unfeeling robot arm"

Zim usually shows little to no affection, often claiming to "need no one", but he occasionally lets a softer side of him slip by accident. In "Parent Teacher Night", when Zim thought back to when he was born, he remembered the first thing he ever said was that he loved the "cold, unfeeling robot arm" that "hatched" him from his incubation capsule and activated his PAK. In "Walk of Doom", he yells at GIR for leaving behind his guidance chip and stranding them in the middle of the city but when GIR starts to cry, he forgives GIR (despite the fact that he was crying because he missed the cupcake he ate).

If he removes his PAK, with the exception of the life support and personality components, perhaps all the aforementioned negative traits of his personality can change.

Zim and Dib fighting.

Strangely, it would seem that Zim also relies on the presence of his mortal enemy, Dib, for motivation. He said in "A Room with a Moose" that his mission might not be as "exciting" without Dib around to "annoy him", but also seems to dwell on the big-headed human quite a bit, sometimes more so than his actual mission.

In fact, Zim enjoys tormenting and humiliating Dib even if it is unprovoked that he would just do it for the fun of it, making Dib's hatred for him real and his efforts to beat the Invader all the more personal. This importance was particularly highlighted in "Mopiness of Doom": When Dib briefly decided to give up his pursuit of Zim, the Irken lost all motivation to take over Earth or do anything in general.

Zim's plan begins.

In Enter the Florpus, it was shown that Zim is not as delusional towards the relationship he had with his leaders as it was shown that could see the truth (even if temporarily) since he could no longer be in denial after seeing the Massive’s flight plan and seeing that Earth was “Smillions of light years away from the Irken Armada, this turned him go into a mopping mess once he realized that he doesn’t have the respect of his leaders was just about ready to give up on his mission and allow Dib to expose him to the rest of the human race.

this depression however didn’t last for long as it was shown that after Zim truly has the potential to be an actual threat if he puts his mind to it, as he successfully hijacked Professor Membrane's Peace Day ceremony, but only after Dib unintentionally inspired him (and he even rubs it in his face about it), it could be said that his determination to get back on the Tallest good side was the driving force behind his successful teleportation of Earth, making it clear that there is nothing Zim wouldn’t do to earn the approval of his leaders.

Zim has won!

Earth was moments away from being destroyed and taking humanity with it, Zim showing a complete indifference towards his own life because his mission, even if it was his last one, would've been complete.

Zim sounding so triumphant while stepping into his own doom is quite fanatical because his loyalty to the Irken Empire knows no bounds and he is no doubt willing to go out like a soldier doing his duty. Despite his incompetence in many areas, Zim is actually shown to be intelligent despite Gaz's continued claims of him being stupid. He is an excellent engineer, being able to tool with many devices and equipment. He has a very impressive arsenal, and he was able to fix GIR's behavior using a behavioral modulator and enhance his guidance chip. He also created Minimoose, who has been known to be very powerful and dangerous (although Zim doesn't know how to use him properly).

Like Gaz, Zim is a very skilled pilot of extraterrestrial spacecraft. However, in some episodes, he is shown crashing and his ship in flames, which hints at the possibility that while he can pilot certain ships, he is prone to accidents (in a similar manner to human car drivers).

Throughout the show, there are subtle but noticeable hints about Zim's (and his people's) biology. He is shown to do many things that no human could do yet, hinting that he might have powers or inhuman abilities of some sort. Zim has been shown to have super strength - in "Attack of the Saucer Morons", he body slammed a woman who was twice his size and overweight and knocked her over, while in "Backseat Drivers from Beyond the Stars", he is shown throwing a child into another person hard enough to knock them off their feet. However, Dib was easily able to pin him down for a short moment in both "Megadoomer" and "Bolognius Maximus", though this could have been because he was caught off guard.

He is shown to be very fast and agile. In "FBI Warning of Doom", he is able to evade most of the booby traps set in the mall, in "The Frycook What Came From All That Space", Zim was able to outrun Sizz-Lorr, and he was also able to outrun Dib in "The Nightmare Begins".

He also seems to have inhuman stamina as he doesn't need to sleep (thanks to his PAK). And while he still eats food, Zim is seen to have the ability to go a substantial amount of time without eating as he (supposedly) didn't have any food on his six month trip from Conventia to Earth.

Zim is also shown to have incredible durability, as he is shown taking hits from stronger enemies such as Oog-Ah, Sizz-Lorr, and Sergeant Hobo 678. In many episodes, GIR has been shown falling directly on his head, but he's usually fine afterwards. He has also survived falls from heights, such as in "Battle of the Planets" and "Walk of Doom". He also has been seen surviving crashes; in "Attack of the Saucer Morons", Zim survives two crashes (the first in his Voot Runner, the second in the Voot Carrier) and he also survived an even more disastrous crash in "Hamstergeddon". In "Zim Eats Waffles", Zim was attacked by a demon flesh eating squid and zombie soldiers and was only covered in bruises. In "Tak the Hideous New Girl", he and GIR are thrown into the Voot Runner, causing it to fall from the sky, and he walks away unharmed. In "Battle of the Planets", Zim is shown to be impervious to fire (or at least physically resistant to it).

At the end of Enter the Florpus, Zim's head is caved in by a puppy GIR had recently shot into space. While not shown, he most likely survived this and was only knocked unconscious, this evidently showed that Zim is extremely lucky, as he has survived countless incidents that would have ended in certain death, as exampled above.

Zim has been shown to have regenerative powers, as he's been shown to heal from bruises, broken skin (or skin deformities), and broken bones. He has healed from a popped zit, meat fused to his head, and his skin torn off his head and body