Here are the season one episode names, the air dates, and their episode codes. Season one first aired in 2001-2002 on Nickelodeon. Season one contains the majority of the episodes ever made of this series.
Pilot -- aired May 11, 2000, code 0
The Nightmare Begins -- aired March 30, 2001, episode 01
The Tallest send Zim on a "mission" to Earth to get rid of him.
Parent Teacher Night -- aired April 6, 2001, episode 03A
Zim built robot parents as part of his cover on Earth. He uses them to attend the parent-teacher conference at his school.
Walk of Doom -- aired April 6 2001, episode 03B
Zim improves GIR's guidance chip and decides to test it out by getting lost in the city. He forgot to check to make sure GIR brought the chip along. GIR had indeed removed the guidance chip and left it at the base, and they do indeed become horribly lost.
Bestest Friend -- aired April 13, 2001, episode 02A
To appear more human and normal, Zim adopts a best friend from one of the small group of outcast kids at his school.
NanoZIM -- aired April 13, 2001, episode 04B
Dib finally sneaks into Zim's base and takes pictures which he stores on a floppy disk. Zim enters Dib's body trying to erase the memory of where Dib stashed the disk.
Germs -- aired April 20, 2001, episode 04A
Zim becomes completely germ-phobic after watching a germ-viewing product video on his lab computer screen.
Dark Harvest -- aired April 20, 2001, episode 02B
To appear human, Zim steals the organs of several children at his school when Ms. Bitters sends him to the nurse's office for a case of head pigeons.
Attack of the Saucer Morons -- aired April 27, 2001, episode 05A
A group of alien true believers claims Zim's ship when he leaves it and plans to retrieve it later. when Zim returns, the capture him and then worship him when they discover he is a real alien.
The Wettening -- aired April 27, 2001, episode 05B
Dib discovers Zim can be harmed by water.
Career Day -- aired May 4, 2001, episode 06A
After taking a career placement test, Dib is paired with a paranormal investigator and Zim is sent to McMeaty's for fast food work.
Battle Dib -- aired May 4, 2001, episode 06B
Dib endures many challenges just to gain access to his own father to sign his permission slip. Gaz is several steps ahead of her brother at every turn. This is one of three episodes where Zim doesn't appear.
A Room with a Moose -- aired August 17, 2001, episode 09A
Zim sends his classmates on a bizarre field trip on a hijacked school bus.
Hamstergeddon -- aired August 17, 2001, episode 09B
Zim turns the class hamster into a giant monster, but has to team up with Dib when it attacks his base.
Invasion of the Idiot Dog Brain -- aired August 24, 2001, episode 08B
GIR's brain takes over the base's operating system and uses the it to go to a fast-food Mexican restaurant drive-thru.
Bad, Bad Rubber Piggy -- aired August 24, 2001, episode 07B
Zim sends several rubber piggies into the past to stop Dib from tampering with the present, but it backfires.
Planet Jackers -- aired August 31, 2001, episode 07A
Zim battles two planet hijackers who want to use the earth as fuel for their dying sun.
Rise of the Zitboy -- aired August 31, 2001, episode 08A
Zim uses his giant hypnotic pimple to get Dib to tell him the weakness in his base's security.
Plague of Babies -- aired September 7, episode 10A
Zim discovers a squad of aliens living on earth who look like human babies. They were stranded years ago and try to steal Zim's ship to return to their home planet.
Bloaty's Pizza Hog -- aired September 7, episode 10B
Gaz saves Dib after Zim kidnaps him so they can go on their annual family dinner with dad at Bloaty's Pizza.
Bolognius Maximus -- aired September 21, episode 12A
Zim infects Dib with a virus that slowly turns him into a log of bologna, but Dib fights back by infecting Zim with the same virus. They end up working together to find a cure.
Game Slave 2 -- aired September 21, 2001, episode 12B
In another of the the three episodes where Zim doesn't appear, Gaz stalks another gamer who took the last Game Slave 2 game that was rightfully hers.
Halloween Spectacular of Spooky Doom -- aired October 26, 2001, episode 16
As a result of Dib's experiments, Zim and Dib are trapped in an alternate universe where the only exit is through Dib's head.
Mysterious Mysteries -- aired March 22, 2002, episode 14A
Dib goes on the Mysterious Mysteries TV Show to tell the world about Zim. To his surprise, Gaz, GIR and Zim also appear to tell their sides of the story.
Future Dib -- aired March 22, 2002, episode 15B
Zim captures Dib with a Dib robot replicant while he tries to destroy earth.
Door to Door -- aired March 29, 2002, episode 11A
Zim's class sells candy bars for the school fund raiser.
FBI Warning of Doom -- aired March 29, 2002, episode 11B
Zim receives a threatening phone call from the video store to return an overdue video when he sees the FBI warning as GIR replays it. Fearing his mission is in jeopardy if the video isn't returned immediately, Zim battles mall security to return it after business hours.
Battle of the Planets -- aired April 5, 2002, episode 13
Zim and Dib discover that two of the planets in the solar system are actually spacecraft created by alien civilizations, and use them to battle each other.
Abducted -- aired April 12, 2002, episode 14B
Zim and GIR are abducted by idiotic aliens as human and dog specimens, but escape easily.
The Sad, Sad Tale of Chickenfoot -- aired April 12, 2002, episode 17A
The last of three episodes where Zim doesn't appear, Dib sets out to disprove the legend of Chickenfoot, who is really a man stuck in a chicken costume by a defective zipper.
Megadoomer -- aired April 26, 2002, episode 19B
Zim is accidently shipped a super robot with a cloaking device and uses it to try to kill Dib.
Lice -- aired April 26, 2002, episode 18A
An outbreak of headlice sends a lice hunter to the school to investigate. She discovers the only ones not infested with lice are Zim and Ms. Bitters.
Tak: The Hideous New Girl -- aired May 10, 2002, episode 20
This episode was aired out of order (as many were) and was meant to be the season finale. Tak, the pretty new girl, joins the class and is instantly beloved by the other children. Zim thinks she is in love with him until she reveals she is Irken and has come to destroy Earth, take Zim's mission and impress the Tallest.
GIR Goes Crazy and Stuff -- aired May 24, 2002, episode 17B
Zim tries adjusting GIR's behavior, but things go wrong when GIR sees Zim himself as a threat to the success of their mission on Earth.
Dib's Wonderful Life of Doom -- aired May 24, 2002, episode 19A
Someone throws a muffin at Zim, so Zim simulates Dib's entire life to find out if Dib threw it.
Hobo 13 -- aired July 12, 2002, episode 15A
The Tallest send Zim to the training planet Hobo 13 where he must succeed at a number of extremely difficult tests to prove his is worthy of new equipment. There are wagers going wild all over the Irken Empire as to Zim's outcome of the challenges.
Walk for Your Lives -- aired September 28, 2002, episode 18B
Originally meant to air next to the Hobo 13 episode, Zim causes an extremely slow explosion that he must put out before it destroys the city and his base.
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