In the episode "Planet Jackers" a female bobble head figure with large poorly clothed breasts can be seen very briefly.

In the episode "Parent Teacher Night" Zim has a brief flashback of himself being born in which he is completely nude.

In the episode "Walk of Doom" a poster in the background that says "stop making babies!" can be seen very briefly.

As with every cartoon, there is some adult humor and hidden innuendos in many episodes.

An image of GIR covered in blood, known as "bloody GIR" is cleverly hidden throughout certain episodes as an easter egg, but is only visible for about one frame at a time. You'd have to pause the episode at the exact right second in order to see bloody GIR.

Very frequent use of laser guns and other sci-fi weapons. Tons of chase scenes, hand to hand combat, harsh bullying, explosions, machine battles and mass destruction of cities and entire planets. There are prolonged and intense action/violent scenes in almost every episode.

In most episodes, Zim tries to take over/destroy the Earth or destroy/enslave all of humanity. This goal leads to a ton of violence.

Episodes occasionally feature gory themes, such as the episode "Dark Harvest" which is about Zim harvesting organs from living children and then eating them. Zim briefly hacks up a child's intestine, though it's not bloody per se, it's still rather macabre. It's also worth mentioning that "Dark Harvest" doesn't have a happy ending as Zim wins and gets away with his actions.

Read the "frightening & intense scenes" category since many of the scenes in that category also have violence and/or gore.

In the episode "Bestest Friend" two robotic claws rip a kid's eyes out, (and not in a comedic slapstick way that is meant to be visually appealing; it's actually pretty grim) but the shot pans to his shadow on the wall as this action takes place. Later in the episode, the same kid falls from a great height and is implied to have died as a result of this. The writers were forced to add tiny details suggesting he survived, but the original intent is still present.

Another episode called "Game Slave 2" has a child fall down fifty stories in an elevator. He is later shown to have survived, but, once again, the original intent was for him to die.

In "Planet Jackers" when Zim crashes his spaceship into an invisible barrier, one of his eyeballs falling out of it's socket can be seen for a split second. In "Walk of Doom" Zim's eyes burn up after he stares at the sun. In "The Nightmare Begins" Almighty Tallest Purple gets shot in the eye with lasers a few times. All three of these scenes are brief and have no lasting injuries.

Instances of: heck, dang, gosh, darn, cruddy and what the...

Characters will very often verbally threaten to kill, injure, destroy or dissect each other.

No swearing, but constant use of name calling, threats and other verbal insults.

The characters watch a brief commercial for Aspirin in the episode "Parent Teacher Night".

Some minor characters and background characters are sometimes seen with a pipe in their mouths.

Not all episodes have happy endings or conflict resolution. But if the main characters are mutated, injured or killed at the end of a episode, they always return intact for the next episode.

Nickelodeon received 103 complaints from angry parents, saying that their children were disturbed by the mutated Santa in the Christmas special. This is just one of the many complaints parents had with the series.

The "Halloween Spectacular of Spooky Doom" has some particularly dark and nightmare-ish imagery that children may find frightening.

Sometimes characters will be turned inside out revealing their internal organs; this is done in an intentionally gross way, with large pulsing veins, a dark color pallet, bodily fluids leaking out etc. young kids may find this to be disgusting or unsettling. ("Halloween Spectacular of Spooky Doom"; "Dark Harvest"; "Bloaty's Pizza Hog")

There are many disgusting scenes and stories that may make some people, regardless of age, uncomfortable. For reference, the episodes: "Germs", "Lice", "Bolognius Maximus", "Rise of the Zitboy" and "Dark Harvest" have some of the most disgusting imagery/concepts in the series.

Invader ZIM is a very dark, cruel, violent, sarcastic and satirical show, especially for one on a children's network. The content varies from episode to episode, but some children may find this show to be too frightening, disgusting or disturbing. The series has an intentionally dark and unfriendly atmosphere, several episodes play out like a horror movie and there is never any genuine affection or warmth between characters.

A very disturbing and controversial episode called "Dark Harvest" revolves around Zim harvesting organs from children. A man in real-life named Scott Dyleski murdered his neighbor and said he did so because this episode made him fascinated with collecting body parts. The people who defended Dyleski said that these comments were made in jest, but they also said that Dyleski is innocent, which is clearly false. Bottom line - an episode of Invader Zim might have inspired a real-life murder.

Some of the experiments performed on the children in the episode "Lice" vaguely resemble Nazi human experimentation. In fact, the episode "Lice" was originally going to be called "Lice Nazi" but Nickelodeon denied this title.

Some kids may find Gaz's cynical and demonic nature to be unsettling and/or frightening, particularly in the episodes "Gaz, Taster of Pork" and "Game Slave 2".

Many of the background characters and side characters have large pulsing boils or warts, hideous deformities, giant scars on their faces and/or other disgusting and unappealing features. Very young kids may find these character's appearances to be unsettling.

There are many episodes with plots centered around harsh bullying and/or revenge. This includes, but is not limited to the episodes: "Bolognius Maximus", "Game Slave 2", "Gaz, Taster of Pork", "The Wettening", "Bad, Bad Rubber Piggy", "Megadoomer", "Tak, the Hideous New Girl", and "A Room With a Moose". In all of these instances, the problem, if solved, is solved with cruelty and/or violence. Some viewers may find this upsetting.

In the episode, "Zim Eats Waffles", Zim briefly probes and experiments on the brain of a child. In the episode, "Bloaty's Pizza Hog" Zim performs a vivisection on Dib by taking all of his organs outside of his body. This action is done off-screen, but a pile of his organs outside of his body is briefly seen on-screen and although it's not bloody, it's still pretty gross looking.

In the episode "Bad, Bad Rubber Piggy", Zim physically harms Dib multiple times in rather harsh (although very exaggerated) ways which causes Dib to suffer a variety of lasting injuries, each one worse than the last. Zim eventually succeeds at killing Dib off (which was his plan), but Dib quickly comes back to life.

Almost all of the music in the series is suspenseful and/or horrific sounding.

There's some scenes that are meant to shock viewers and some scenes that are a little bit graphic, but these scenes are usually brief.

In one episode, Dib is seen doodling a picture of Zim strapped to a table and being vivisected.

Read the "violence & gore" category since many of the scenes in that category also have frightening and/or intense scenes.

In the episode "Bestest Friend" a kid has his eyes ripped out by two claws. Only a shadow of this is shown and his eyes are replaced with robotic ones but we can hear him screaming in terror as horrific music plays. Later in the episode, the same kid is attacked by a squirrel and falls off of a tall building as the screen turns red and fades to black.

In "Game Slave 2" a kid is inside of an elevator that snaps and falls down fifty stories; he is later shown to have survived.

There are multiple scenes in which very minor characters are crushed, swallowed whole, blown up etc. and it is NOT shown if they survived.

The bulk of the episodes "Mortos der Soul Stealer", "Dark Harvest", "Halloween Spectacular of Spooky Doom" and "Gaz, Taster of Pork" are based heavily on dark and horror-filled themes amongst the sillier nature of their plots.

The uncut edition of the Christmas special has an on-screen suicide joke, in which debris falls on a crowd of people and one man holds out his arms, smiling and happy to be crushed to death. The impact was one of the things cut out in the cut edition. (It's worth noting that the uncut edition of the Christmas special can be difficult to find.)