This is a description of the episodes from Green Lantern: The Animated Series. See that page for details.
It includes potholed tropes.
Spoilers are not hidden.
Episode #1: Beware My Power, Part 1The Red Lantern Corps are killing off Green Lanterns who live on the edges of the Corps' territory, so far away it takes months to reach. When Hal Jordan finds that their masters The Guardians of the Universe are not doing anything about it yet, he steals an experimental starship (controlled by a sentient computer he names Aya) to go there. His mentor Kilowog comes along. They manage to save a Lantern named Shyir Rev from the red ones but the ship's engine breaks, leaving them stranded in the sector.
- The rage-powered red rings seem to be stronger than the green ones, at least in sheer output.
Episode #2: Beware My Power, Part 2Chased by the Red Lanterns, the Green Lanterns hide on Rev's homeworld. However, Atrocitus, leader of the Red Corps, tells them to give themselves up or he'll destroy the planet, forcing a reluctant minion, Razer, to set up the device. Hal faces Atrocitus but is beaten. Rev dies buying time for Kilowog to evacuate the populace before the planet explodes. Razer is then captured by the Green Lanterns.
- It is implied that Hal is one of the few Green Lanterns to have a Secret Identity.
Episode #3: Razer's EdgeHal and Kilowog deliver Razer to a space prison ran by the Spider Guild. However they suspect something is wrong and return to investigate, only to be captured when special crystals in the prison cancel their rings' powers. Razer, who is repentant about blowing up Rev's planet, is freed by Aya, who then convinces him to help save Hal and Kilowog. After dealing with the alien spiders, Hal returns Razer's power ring and decides to bring him along with them.
- We find out that Razer became a Red Lantern after the woman he loved died.
- The Spiders ate their prisoners after torturing them inside their own minds.
Episode #4: Into the AbyssWhen a spaceship full of unhatched eggs from an endangered alien species is dragged towards a "pinhole" in space, Hal, Kilowog and Razer work desperately to save it. However Kilowog's mistrust for Razer turns violent at a critical moment. They are saved with Aya's help.
- Aya obtains a humanoid body in this episode.
Episode #5: Heir ApparentThe heroes try to recruit a new Green Lantern to battle the Red ones, but first he must engage in a duel to gain the hand of his queen. But when he is found dead, Hal must take his place, while the others look for the killer.
- This is the first episode to be taken directly from the Green Lantern comics.
Episode #6: Lost PlanetAya tracks Rev's ring to a planet which is about to be hit by an asteroid. After delaying the asteroid, the crew disembarks to find the ring's owner. None of the inhabitants seem to have it, but they — and the planet itself — are more than they appear to be at first glance.
- Mogo and Saint Walker are introduced.
- This episode is loosely based on Alan Moore's comic "Mogo Doesn't Socialize."
Episode #7: ReckoningRazer breaks ranks with the Green Lanterns so he can deal with Atrocitus personally, but things don't go quite as planned. Hal learns the origins of the Red Lanterns.
- Atrocitus claims responsibility for the war on Razer's planet and the death of his wife.
- Razer gets a Red Lantern battery to recharge his ring.
- The backstory of the Red Lanterns is revealed: The Manhunters destroyed their world.
- The Red Lanterns have a fleet of warships.
Episode #8: Fear ItselfHal and Kilowog find themselves caught in the middle of a war while searching for food. Kilowog ends up in a camp of pig people similar to himself, while Hal ends up with the jellyfish creatures that are supposedly antagonizing them.
- The yellow crystals show up again. Not only do they nullify Green Lantern energy, they drive people paranoid with prolonged or direct exposure.
- Hal to Kilowog while the latter is under the influence of the yellow fear crystals: "Kilowog, I know you're in there. Think, buddy, think about what you are doing!"
Episode #9: ...In Love and WarThe heroes meet the Star Sapphires Corps, power ring-wielders who wield The Power of Love. Unbeknownst to the heroes, the Star Sapphires' interpretation of love leads them to imprison males on their home planet, and the Green Lanterns are their next targets. To this end, Galea, Kilowog's Love Interest from the previous episode, and Carol Ferris are recruited to help imprison them. This backfires when Aya and Razer investigate Kilowog's disappearance, while Carol's ring makes her violently jealous. Hal helps Carol reject the ring's influence, allowing her to remove it, and Carol is sent back home. Hal then rescues Kilowog and escapes with his friends.
- The Zamarons (Star Sapphires) are the former mates of the Guardians of the Universe, like in the comics.
- In the comics, the Zamarons used gemstones as the focus of their powers (thus the name), not rings.
- Kilowog's new love interest (from the previous episode) becomes a Star Sapphire, as well. Unlike Carol, she remains one.
- Aya's appearance is revealed to be based on Razer's dead wife, a fact which he had failed to notice (though the viewers might have).
Episode #10: Regime Change
Iolande's brother, Ragnar, becomes a Red Lantern and conquers their world with the Reds' help, even setting up a "liberator" (the device the Reds use to destroy planets). The heroes arrive to help but are overpowered and must hide. Ganthet wants to use his prototype weapon, which uses hope as a power source, to aid them, but Appa has him exiled for breaking the Guardian code of indulging in emotion.. With help of Sayd, Ganthet returns to Oa, activating his prototype: a Blue Lantern battery. Its power doubles the strength of the Green Lanterns while nullifying the powers of the Reds, earning the heroes a decisive victory over the Reds and giving them the power to remove the Liberator safely.
- Ganthet is still in exile at the end, but willingly so.
- The Guardians sent an army of Green Lanterns to the Frontier to help, but it will take them 18 months to get there. Meanwhile, Oa is defenseless.
- The blue hope energy is what powers the Blue Lanterns in the comics.
Episode #11: Flight Club
The Red Lanterns are looking for a code that will activate "The Lighthouse" an ancient device that can open a path through The Maelstrom, a barrier between their territory and the Guardians', so their space fleet can pass through. The code was known only by a Green Lantern explorer who was imprisoned in the Space Prison (from episode #3). The Green Lanterns are sent by The Guardians to find it first, but the explorer is already dead and the only one who knows the code now is Byth Rok, a Thanagarian criminal. The heroes must make a deal with the treacherous man to obtain it before the Reds arrive.
- Byth was the Silver Age Hawkman's first foe in the comics.
Episode #12: Invasion
The crew heads for the Lighthouse to destroy it and prevent the Red Lantern invasion, but the Reds, having obtained the access code from Byth, have beaten them there. The heroes eventually succeed in their mission but Atrocitus blasts a hole through the asteroid field anyway using his planet-killer bombs. When Hal attempts to arrest him, Atrocitus outmanuvers him and steals the Interceptor.
- Saint Walker's journey up the mountain is a reference to the comics, except he went up with his family in that continuity (who died along the way). Here his world was ravaged by the Red Lanterns.
- Saint Walker finds the Blue Lantern battery and gets a blue power ring.
- Aya has Taken A Level In Badass. She and later, Hal lampshade this: "As you would say, I am no longer a rookie."
- Aya is reprogrammed into helping the Red Lanterns (by one of Mogo's prisoners from episode #6.)
Episode #13: Homecoming
Atrocitus uses Aya to bypass Oa's defenses and land on the planet. He begins his assault while the guardians hide in the control room.
Hal devises a plan to reach Oa in time to save The Guardians, but Kilowog stays behind to hold back the Red Lantern Armada. The remaining members of the crew ask for aid from the Star Sapphires, who have reformed since their introduction. They use their technique that teleports a person to the one he or she loves, and it sends Hal to Earth although it gives him temporary amnesia; Carol helps him remember. They also send Razer straight to the Interceptor, implying that he loves Aya. He saves her.
Meanwhile Saint Walker and Mogo help Kilowog stop the alien Armada.
Hal arrives on Oa in time to save the Guardians and ultimately defeats Atrocitus. He and Appa then convince the rest of the Reds to leave in peace with an admission of guilt and an offer to rebuild the forgotten zone.
- This episode is Saint Walker's debut as a Blue Lantern.
- The finale of the first Story Arc.
Episode #14: The New GuyWhen Hal returns to Earth, he finds out he's been replaced as the Green Lantern of Sector 2814 by Guy Gardner, while the Anti-Monitor and the Manhunters begin to carry out their plans.
- Guy Gardner and the Anti-Monitor are introduced to the series.
Episode #15: Reboot
The threat of the Anti-Monitor forces Hal to try and reassemble Kilowog, Razer and Aya as a team to help the new Honor Guard.
- Hal recruits Aya and Kilowog, the former having been rescued from dissection by the Guardians. Razer is noted to be "on sabbatical."
- Green Lanterns Tomar-Re, Ch'p, Larvox, and Chaselon are introduced.
Episode #16: Steam Lantern
After a blast from the Anti-Monitor, Hal is transported to an alternate world where steam still rules as a powersource.
- When we first see the sun through Duke Nigel's telescope, the sun was red. The red star is the last true living phase of the sun.
- The Steam Lantern debuts.
- The Steam Lantern describes another Green Lantern who wore a red shirt and cape, a clear reference to Alan Scott, an older Green Lantern whose powers were magical in nature.
Episode #17: Blue Hope
Hal and his team must come to the aid of their old friend Saint Walker when the Manhunters attack the world where he is training his new Blue Lantern Corps.
- Ganthet is now on Odym with the newly founded Blue Lantern Corps.
- Brother Warth is introduced.
- Aya has her body back. (the reason how she gets it back is not fully revealed until episode 20; she keeps spares around)
- Razer returns.
Episode #18: Prisoner of Sinestro
Green Lantern Sinestro unknowingly unleashes a dangerous creature on board the Interceptor.
- Sinestro is introduced.
Episode #19 Loss
The alliance between the Green and Red Lantern Corps is threatened by the arrival of the Manhunters.
- The Anti-Monitor is a creation of Krona in this continuity, designed to be capable of anything. It predictably turned on him.
- Zox has named himself Prime Magistrate of the Red Lanterns, and they're in the process of rebuilding their world.
- Two days after this episode aired, Cartoon Network announced the cancellation of this and Young Justice.
Episode #20: Cold Fury
Unable to escape the Anti-Monitor, the team prepares to fight him, with some help from the Red Lanterns.
- The Anti-Monitor is defeated, but Aya, having shut off her emotions, takes over his body for her own purposes.
Episode #21: Babel
The team is stranded on an alien planet without the use of their rings.
- This episode was partially inspired by The Hangover.
- Giancarlo Volpe and Jim Krieg initially suggested using the translation barrier as a Running Gag, but Bruce Timm said that they should dedicate a full episode to it instead.
Episode #22: Love Is a Battlefield
Zamaron is targeted for destruction, and a duel of champions is proposed.
- This time around, Carol actually keeps her Star Sapphire ring.
Episode #23: Larfleeze
The team finds the Orange Lantern Corps.
- Larfleeze is introduced.
Episode #24: Scarred
The Green Lanterns use yellow crystals to try and stop Aya's rampage.
- The Science Director returns as Scar.
- Aya's origin is revealed.
- The Book of the Black and an Alpha Lantern prototype are shown in Scar's study and laboratory, respectively.
Episode #25: Ranx
The Green Lanterns find the Anti-Monitor's head in working order.
- Green Lanterns Guy Gardner, Tomar-Re, Ch'p, Chaselon and Larvox all return.
- John Stewart is the new Green Lantern of Earth.
Episode #26: Dark Matter
The Green Lantern Corps makes their final stand against Aya.
- This is the series finale.
- It is heavily implied that Razer would have become a Blue Lantern had the series continued.