An alien named Zim from the planet Irk is sent on a secret mission to conquer Earth, not realising that his leaders were just trying to get rid of him and hoped that he would die. Once there, Zim manages to disguise himself as a human child, but one boy named Dib sees through his disguise.
Stand back, ignorant Earth filth. Invader Zim has been sent from the planet IRK on a mission of doom. Disguised as a child and accompanied by GIR, his robot, Zim has come to assume control of Earth. But, a wrench named Dib interferes with his plan.—Hulu
The Irken armada is poised to conquer the universe, but it would be a lot easier without Invader Zim. Thickheaded, brash, and overzealous, Zim has been banished into food service for wrecking the Irken home planet. He begs the Almighty Tallest for a second chance to reclaim his honor. Zim is sent on a "secret" mission to a planet far away on the edge of the universe - Earth. Now Earth's only hope rests with a young UFO-hunting paranormal enthusiast named Dib. Seeing through Zim's human disguise, Dib makes it his sole mission to defend our planet from this fiendish alien menace.—iTunes
Invader ZIM is an eccentric alien soldier from the planet Irk. He was banished from the Irken Empire after nearly destroying his home planet on an early mission. After begging his superiors, the Almighty Tallest Red and Purple, for another chance, they decide to get rid of him once and for all. They trick him into going on a "secret mission" to an obscure planet at the edge of the universe, a planet with the unlikely name of Earth. Their trick works, and now ZIM is intent on bringing down the human race. He disguises himself as a schoolboy, and now the only person who can stop him is one kid - Dib Membrane, a somewhat insane paranormal researcher, who sees straight through ZIM's disguise and is intent on stopping his reign of terror. But neither ZIM nor Dib is very good at their job, and what results is everything imaginable, from a giant hamster destroying the city to both ZIM and Dib being turned into bologna meat.—Anonymous
The universe's greatest threat, the Irken Empire, is slowly taking over the known universe through, as it seems, sheer dumb luck. An Irken Invader (Ex-Invader, actually), ZIM, who single-handedly destroyed an entire military operation in his past, has returned to his leaders, begging for another chance to give himself a good name. They do- sort of. Actually, they just send him on a joke mission to get him out of the way. They pretend to see his worth, give him a junk robot, and send him off, hoping he'll die on the way. To their surprise, he lives, and actually finds a planet to devastate, which is-what a surprise-Earth. However, he has landed in the wrong place. A paranormal investigator, Dib, has seen through his disguise, and is hot on his trail. It sounds like an average alien story, but it ain't. Did we mention Dib is ten years old, and considered stupid or crazy (though clearly not) by many of his peers? And that ZIM isn't the best invader in the world? Or that neither of them is very good at stopping each other? Or that this show will have you rolling on the floor laughing? If you can get your hands on the Nicktoons channel or the DVDs, you may as well find out...—TheLetterP
The series centers on Zim (voiced by Richard Steven Horvitz), a member of the imperialistic Irkens, an extraterrestrial race from the planet Irk, who are bent on universal conquest and whose social hierarchy is based solely on height rather than any type of skill or intellect. The two Irken leaders, known as The Almighty Tallest (Wally Wingert and Kevin McDonald), rule the Irken Empire together because they are the tallest individuals in their society and exactly the same height. As recounted in series premiere, "The Nightmare Begins", Zim is a delusional Irken outcast who is very short, and also overzealous, narcissistic, and megalomaniacal. He was banished to the Irken food court planet, Foodcourtia, for absentmindedly nearly destroying Irk and his own race during their first invasion known as Operation Impending Doom I.
When Zim learns the Irkens are planning a new invasion called Operation Impending Doom II, he, not understanding the purpose of his exile, "quits being banished" and leaves Foodcourtia and travels to the convention center planet called Conventia, for the Great Assigning, an event where Irken Elite soldiers are chosen to become Invaders and are then assigned by The Tallest to a planet. Invaders are soldiers whose missions are to blend in with the indigenous life forms of their assigned planet, collect information about the planet and its inhabitants and prepare the planet for conquest by the Irken Armada. Zim is determined to regain his status as an Invader and pleads with The Tallest to assign him a planet. In a desperate act to get Zim as far away as possible and ensure he would not ruin things the second time around, The Tallest send Zim on a fake "secret mission" to a "mystery planet" located on the outskirts of their known universe which they do not think even exists, in order to keep him occupied and away from the real invasion. Zim is joined in his mission by GIR (Rosearik Rikki Simons), an ineffective and erratic Standard Issue Information Retrieval (SIR) unit which was hastily made out of spare parts found in a trash can.
After a six month long trip across the universe, Zim finally arrives at this "mystery planet" which not only really does exist, but also coincidentally happens to be a dark, dystopian, and satirical version of Earth. Delighted with his find, Zim quickly goes to work and succeeds at setting up his base of operations in a random suburban area on Earth, much to the dismay of The Tallest. Due to his short stature, Zim disguises himself as a human child, albeit one with a green complexion that he explains away as a "skin condition", and attends a local school (spelled "Skool") in an attempt to collect knowledge about Earth and learn the planet's weaknesses. The remainder of the show focuses on Zim's time "infiltrating" the human race at school or at his home base, planning attempts at world domination, and the enslavement of humanity. Opposing Zim is his classmate Dib (Andy Berman), a paranoid young boy who is obsessed with the paranormal and supernatural and the only human (besides his sister) who sees through Zim's disguise. Dib is determined to expose Zim as an alien and thwart his plans for world domination, despite the hostility and mockery he receives from his oblivious peers for doing so.
Supporting characters include Dib's cynical and apathetic sister Gaz (Melissa Fahn); Zim and Dib's demonic teacher Ms. Bitters (Lucille Bliss); and Dib and Gaz's famous, but neglectful father Professor Membrane (Rodger Bumpass). Later in the series, other alien characters begin to appear, including Tak (Olivia d'Abo), a fellow Irken seeking revenge against Zim; Lard Nar (Fred Tatasciore), the leader of a resistance group called The Resisty who wants to overthrow the Irken Empire; and Sizz-Lorr (Jim Wise), Zim's former Irken employer on Foodcourtia who attempts to recapture his employee.
Apart from eight double-length episodes (including the debut), each episode is a self-contained storyline. Some occurrences from previous episodes are mentioned, but there is little continuing storyline other than the main invasion plot. However, towards the end of the show, a larger universe of characters and organizations were introduced to build continuity: Tak appearing and seeking revenge against Zim; Dib's capture and repair of Tak's spaceship to travel through space; resistances to the Irken Empire such as the Meekrob and The Resisty; and other various devices which were becoming more and more a part of the show's central mythology.
