Even anime has done season-ending 'hangers, with The Big O and Zoids Fuzors, not to mention a cliffhanger of truly staggering size at the end of Season 1 of Code Geass (mentioned in detail below).
Let's be perfectly honest here. Code Geass has a very, very, VERY nasty habit of leaving cliffhangers at the end of every single episode, at least in the first season. The season is basically a 25-episode cliffhanger, ending with a scene that quite often leaves viewers screaming at the top of their lungs at their screens.
They also had a bad habit of the next episode beginning after the cliffhanger is resolved, and then drawing it out until a flashback shows how it actually ended.
And then comes the second season, where Every. Damn. Episode. Ends with a cliffhanger of cosmic proportions and every second one is a Wham Episode, to boot.
Parodied in the first episode of Magical Project S, which ends with the then-faceless Pixy Misa saying "you'll have to wait until next week to see who I am".
When D.N.Angel was put on a hiatus by its writer, fans were left hanging for two years in which Daisuke was setting off to find his kidnapped love interest's twin sister, and gets offered by his morally questionable rival for help. Fans were left waiting for two years until the manga was started up again and the arc was resolved.
After completing the aforementioned arc and even getting through another one, D.N.Angel is once again put on an at least six month hiatus with the completion of Part 1...with the massive cliffhanger of Riku finally seeing Daisuke (and Satoshi) transform, and asking if he's Daisuke...or Dark. And that's not even covering the stuff that still needs to be answered after that single chapter.
In True Tears, one of the driving factors for following the story asides the depth of the characters and the compelling love story are the constant cliff hangers on the end of each episode. Several of these tend to shake up things quite a bit.
Bakuman。 is pretty much a cliffhanger in every chapter.
During a meeting to decide which series to cancel, the editors decide to end two out of the three lowest-ranking series. The editors mention that one of the choices was obvious- "they"(either Aoki and Nakai or Mashiro and Takagi) got a warning at the last meeting and weren't able to improve. The chapter ends with the editor-in-chief announcing that he'll end Hideout Door(Aoki and Nakai's first series), and the next chapter begins with his second pick- Detective Trap(Mashiro and Takagi's first series).
The chapter covering the meeting to serialize PCP seemingly ends with the editor-in-chief casting the deciding vote that will reject the series, and result in the main characters no longer being able to work for Jump. In the next chapter, three of the other "no" voters switch sides for various reasons, resulting in it passing 6-1.
Bleach often ends with cliffhangers, especially when one character launches an attack against another. More often than not, the attack is non-fatal (and often, completely ineffective), and the next chapter shows why. If they are indeed fatal, then expect a flashback of the dying character instead.
Several episodes of Death Note, particularly the second-to-last one when Light has Mikami write all his enemies' names in the Death Note, end in cliffhangers.
Hayate the Combat Butler manga started out the current arc with one, and still hasn't resolved it. Leaving the fans to try and figure out how the pieces are going to connect. Doesn't help that the last arc gave us the starting of it, but leaving things vague enough for us to not realize that it was going to be left as a cliffhanger.
Zig-zagged in the anime adaptation of Berserk. The very first scene of the anime takes place a few weeks after the events of the Eclipse with Guts waiting for Godo to prepare the Dragonslayer. After the opening credits, the scene flashes two years later when Guts has a well-established reputation as the Black Swordsman. After defeating an apostle, the rest of the series reveals how Guts became the way he is in the present, starting with his first encounter with soon-to-be Big Bad Griffith. In the last episode, during the climax of the Eclipse, we see Guts screaming in rage and agony at the sight of the demon lord Femto raping Casca just as the credits role in. Although the very last scene reverts back to the very first scene, it is still left unclear as to how Guts managed to make it back from the hell dimension alive or whether Casca survived her ordeal and the viewers are still Left Hanging on this detail as Guts walks into the distance as the Black Swordsman, which is where the anime ends.
Used very very frequently in Brigadoon: Marin and Melan. Especially in the second half of the series, more episodes end with cliffhangers than not.
The Pokémon Adventures FireRed and LeafGreen chapter ends with one of these.
While the (classic) Pokemon anime has several multi-part episodes, its first series finale, denoted by the text "Next Time, A New Beginning!" instead of "To Be Continued...", qualifies. Ash is approaching Hoenn with his Pikachu taken sick as a side-effect of Team Rocket's latest capture attempt. Starting the next series in the following episode was likely done A: To emphasize May's role as the new Deuteragonist and B: to invoke this Trope, as Ash said his goodbyes to his Johto crew in the previous episode; it's just him and Pikachu to start this one off.
Every chapter has a Cliff Hanger in Bitter Virgin. The readers are even left hanging on the last chapter to how the relationship will end up.
The Giant Robo OVA ended on a great, gaping "To Be Continued". While the main conflict is resolved, it's implied that Big Fire still had a few more tricks up their sleeves.
Episodes 5 and 10 of Popotan: the former ends with Mai and Mea being left behind when their house jumps forward in time five years, the latter with Keith incapacitating Mea and making the house travel to its final destination.
One of the things that makes Doki Doki! PreCure different than any other Pretty Cure series different are the cliffhangers. If nothing plot-relevant happens in an episode, the episode will end in a plot-relevant cliffhanger. This is how the show makes every episode tie into its Myth Arc. Of course, some plot relevant episodes have cliffhangers, as well.
Episode 7 ends with Shinako asking Rikuo if he wants to visit her at her apartment. Rikuo's response is not shown until the next episode.
Episode 10 ends with Rikuo getting a phone call that shocks him, but the viewer isn't shown who called or what that person told him. The following episode reveals that Haru called to report that someone broke into her apartment.
Episode 11 ends with Rou spotting Rikuo and Shinako together and demanding to know what their relationship is.
In Attack on Titan, during the Uprising arc, one chapter ends with an enemy having Jean at gunpoint, with a gunshot being heard. It turns out that Armin shot and killed the enemy, saving Jean's life.
At the end of the first season of Sekirei, Minato manages to help Haruka and Kuno escape, which was the focus of the last portion of the season, but the Sekirei plan/battle has just begun, and the ending shows a bunch of loose ends which have yet to be resolved. The main Big Bad and game master even mentions the game is far from over. Fortunately Season 2 has arrived, and covers the next portion of the series.
The end of The Tower of Druaga: The Aegis of Uruk has Neeba and Kaaya abandoning their parties to climb up the heretofore unknown upper half of the tower. Even after the second season started, no one knew what was going on with them and some of those left behind until later in the season.
Chapter 11 of My Younger Senpai ends with Aya Seto getting a text message from her kohai Nana Nanasawa saying that there is something important that Nanasawa needs to tell Seto.
Chapter 23 of Kami eshi JK to OL fujoshi has Ai visit Kasumi's parents. In the middle of a conversation over whether Kasumi will go with her parents or stay in Tokyo, Ai has a breakdown and confesses that she is in a romantic relationship with Kasumi.
In Chapter 10 of A Monster Wants To Eat Me, Hinako has seemingly talked down her best friend Miko, who is secretly a monster, and resolved her fight with Hinako's monster friend Shiori. Miko then suddenly transforms into her monster form and seemingly devours Hinako as the chapter ends. In the next chapter, it turns out that Miko actually bit off two of her tails, sacrificing some of her power.
Shi ni Aruki, as a mystery series has several chapters that end on an ambiguous note.
Chapter 3 ends with Takahito's attempt to murder Tokiko, with her slipping into unconsciousness from blood loss as they had just been stabbed repeatedly in the chest. Chapter 4 reveals that she's still alive, if just barely, and Takahito accidentally kills himself trying to finish the job.
Chapter 7 ends with Rina going missing after confronting Tokiko at the hospital. Chapter 13 opens with the reveal that she was murdered, with her body being among others found in an abandoned house a few chapters prior.
Chapter 16 ends with Natsuki seemingly getting killed by an aging convenience store sign dislodged by a bird flying off, though we only see Tokiko's stunned reaction to the event. Chapter 17 opens with the supposed blood splatter being bird poop. The sign never fell, and Tokiko's shock was just her (and Natsuki) being startled by the bird.
Chapter 18 ends with Sou Aoya confessing to being a murderer and pushing Tokiko into the water to drown her.
Chapter 19 ends with Tokiko unconscious and getting dragged off by Sou, who has revealed himself to be the serial killer the police are looking for. They're shown to be alive and well in Chapter 22, but only because the murderer wished to give them one last meal.
Chapter 23 ends with Koga accompanying Akiyama to Aoya's apartment. When Akiyama opens the door over Koga's objections, Koga looks inside and says, "What... the hell...?", although the viewer is not shown what he saw in there. Several chapters later, it is revealed that they arrived after Tokiko killed Aoya and escaped.
Chapter 24 ends with Tokiko taking Aoya's little sister Ai hostage.
Chapter 25 ends with Tokiko claiming that she killed someone in the past.
Chapter 28 ends with Natsuki about to be strangled by her backpack when it gets caught in a elevator, just as she was about to affirm her friendship with Tokiko despite just learning that she's a murderer. The next chapter has Tokiko manage to save her, only for her to die regardless at the end of that chapter from getting run over by a truck.
The second volume of Goodbye, My Rose Garden ends with Alice begging her maid/prospective girlfriend Hanako not to leave her, then making a major Internal Reveal- that she is Victor Franks, the author Hanako came to Britain to meet. Hanako's reaction is not shown until the next volume.
My Hero Academia: In Chapter 372, Present Mic and Spinner both call out to the imprisoned Kurogiri, hoping he will join their side.
In the manga adaptation of Persona 5, Chapter 50 while Makoto's using Futaba's USB drive to lift data off her older sister Sae's laptop while Sae is in the bath, only for Sae to get out before Makoto's finished. In the next chapter, Makoto manages to buy some time by asking Sae to put bath salts in, enabling her to finish in time to avoid being caught.
Chapter 5, the end of the first manga volume, ends with Kaori telling Shizuku that she always knew about Shizuku being a bully in elementary school.
In Chapter 14, after Ruri and Seri leave following Shizuku's attempted apology to Ruri, Kaori collapses.
In Chapter 15, when Shizuku is visiting Kaori in the hospital, the latter suddenly decides to break up long before the agreed-upon end to their relationship at the end of the summer. The third volume ends here.
In Chapter 30, Shizuku gets a call from Seri informing her that Kaori's condition took a turn for the worse and she is now on the operating table.
Ranma ½ uses them frequently, with an especially notable one being Shampoo's introduction at the end of Chapter 30, "The Waters of Love". Just as the events of the Martial Arts Figure Skating Arc are wrapping up, Shampoo suddenly kicks a hole in the wall and declares that she's there to kill Ranma, leading into her introductory arc in the next chapter.
The last episode of the English dub of Tokyo Mew Mew, halfway through the series, ended this way, with Ichigo, having defeated the Monster of the Week, rushing to meet up with her Love Interest Aoyama. Why? 4Kids was planning to continue it, but they didn't, due to "no merchandise tie-ins", possibly either due to companies not finding the concept of the show interesting, the molds for the Japanese versions of the toys not being able to find anywhere, or the most likely reason, Zakuro's weapon being de-crossed so it wouldn't offend non-Catholics.
The official reason is that 52 episodes was seen as too short by merchandise-companies. 4Kids would have had to have produced at least another season themselves.
Futari wa Pretty Cure MaX Heart has a cliffhanger in episode 5, when Cure Black and Cure White fought together with their new companion Shiny Luminous against Circulas. The battle just began. But the next episode starts in the next morning, Circulas was fine, the girls were fine, nobody knows what happened in this battle and how it ended. There were also no flashbacks.
The anime (the English Dub, at least) of Bobobo-bo Bo-bobo ended 64 episodes in, with the narrator cliffhanging the intense, epic final battle on the horizon... then, to the horror and shock of the entire cast, says it's the last episode that will be aired.
Everyone: This is how you're ending the show?!
At the end of the second episode of Mighty Space Miners, the mining colony on the asteroid Toutatis is in serious trouble: the accidental detonation of an orbiting nuclear warhead has sent Toutatis on a collision course with Earth, and instead of evacuating the colony, the Corrupt Corporate Executives on Earth who financed the enterprise have remotely activated another set of warheads they had previously hidden on Toutatis, which will destroy the asteroid and everyone on it in 36 hours. Only two episodes of this OVA were ever produced, and the cliffhanger is never resolved. (The eventual solution may have involved the miners ejecting the warheads into space in a specific direction and using their detonation to deflect Toutatis away from Earth.)
Pokémon the Series: Black & White has a cliffhanger that ultimately went unresolved. The episode "A Venipede Stampede" led up to Team Rocket finding something linked to the Meteonite in the Desert Resort and Giovanni actually going there to claim it. The episodes that followed this were made, however, but the 2011 tsunami prevented the episodes from ever airing. In the dub, they even removed the cliffhanger at the end of the previous episode since it was apparent that the episodes after it weren't going to air. The final nail in the coffin came with Episode N much later, which retconned the two unaired episodes, and thus the 'hanger resolution, out of existence.
Ino-Head Gargoyle ends with Saejima, Kamata, Akutsu, and Nakajo driving to Ikebukuro to catch the leader of the Blue Rose gang.
Cyborg 009: This is how the God's War OVA ends. The upgraded cyborgs are teleported to the floating island by 001, Himiko greets them by summoning a giant warrior statue and an army of demons, the cyborgs prepare to do battle...and then the screen fades to black with Professor Gilmore saying he's certain that they'll win.
Hybrid × Heart Magias Academy Ataraxia: The anime ends with Grace Sinclavia, Empress of the enemy Batlantis Empire, appearing next to the heroes and revealing that Aine is her long lost sister, then a "To Be Continued" message. They were planning to make more seasons to cover the remaining light novels, but the show was cancelled when its studio filed for bankruptcy.
