Cartoon Network has been host to some of the best anime ever made, but a handful of its best titles faced unexpected cancellations that meant they never reached their full potential.

Western anime fandom owes a pretty massive debt to Cartoon Network. The network’s curation of everything from existential classics like Trigun and Cowboy Bebop to pop-cultural darlings like Death Note, Neon Genesis Evangelion, and Bleach brought them to Western audiences they wouldn’t have otherwise found. Even today, this trend continues: Toonami is now home to Bleach‘s concluding Thousand-Year Blood War arc, a true full-circle moment for longtime Toonami viewers.

But through the years, some beloved stories have slipped through the cracks and not gotten their well-deserved endings, thanks to unexpected cancellations due to budget issues, production problems, and any other number of complications. These series still deserve a watch in spite of being tragically cut short.

Deadman Wonderland

At its core, Deadman Wonderland is a death game anime, similar to Alice in Borderland or Kaiji: Ultimate Survivor. When protagonist Ganta is falsely accused of murder and sentenced to death, he has to clear his name, aided by the mysterious Shiro who apparently knows him. This has to happen within a twisted amusement-park-prison complex where prisoners are forced to wear collars injecting poison that will kill them within three days—unless they continually earn or purchase candy antidotes.

Deadman Wonderland‘s anime adaptation was incredibly strong and intense, but it left out major characters from the source material and started to deviate significantly. Deadman Wonderland left off on a cliffhanger and diverged so much that a second season became impossible. While it wasn’t canceled in the conventional sense, it deserves a mention as a fantastic anime that will never receive a proper ending.

The Big O

The Big O is frequently compared to Batman: The Animated Series, which makes a lot of sense considering Sunrise Studio 6 had animated nine episodes of the latter before beginning work on the former. Many of Batman‘s sensibilities are clearly at work in The Big O: the Dark Deco aesthetics, distinctive art style, and its wealthy, polished protagonist, Roger Smith. But the things that really make The Big O stand out are where the two diverge.

The Big O swaps crime-fighting for mecha action, psychological intrigue, and sci-fi depth, all centered around the pulsing mystery of a domed city where a mysterious cataclysm left survivors without memories 40 years earlier. The first season performed poorly in Japan, cutting its initially planned 26-episode run in half. However, it would find a second life on Toonami and Adult Swim.

With Western audiences receptive, The Big O was revived for a second 13-episode season co-produced by Cartoon Network, leaving off with an ambiguous twist ending that left plenty of room for further exploration. However, The Big O would be shelved afterward right as its biggest mysteries were turned on their heads.

Cyborg 009: The Cyborg Soldier

Cyborg 009 is a renowned long-standing property within the manga world, dating back to 1964. Like many manga of the period, it’s received its fair share of adaptations. One such adaptation, Cyborg 009: The Cyborg Soldier, aired on Toonami in 2003 under the shortened name Cyborg 009. The series has a simple premise—nine people are kidnapped by a shady organization called Black Ghost, then turned into cyborgs that the leader Skull intends to use as human weapons. These cyborgs escape and rebel against this organization, banding together to stop Black Ghost’s apocalyptic ambitions.

Cyborg 009 is a great series with plenty of depth and commentary, but its history on Cartoon Network would seem to show otherwise. The series first aired on Toonami for 26 of the anime’s 51 total episodes, before eventually being moved off primetime to weekly late night/early morning blocks. The final two episodes would never be aired on Cartoon Network at all.

Zatch Bell!

Zatch Bell!‘s cancellation was doubly tragic and undermined its potential to become one of the most beloved modern shōnen anime. The premise of the series is pretty simple: magical otherworldly creatures called Mamodo carry out a tournament to determine the ruler of the Mamodo world. This tournament takes place on Earth, as Mamodo need humans to read their spellbooks. One such Mamodo, Zatch Bell, teams up with a genius named Kiyo Takamine, and the story follows the bonds that develop and conflicts they traverse on their journey together.

Its surprisingly rich emotional core and its unique spin on conventional tournament stories and magical systems led to Zatch Bell! becoming a cult classic, including in America, where it would debut on Toonami in 2005. However, two key problems emerged. First, the anime was canceled after 3 seasons, ending abruptly on a cliffhanger after 150 episodes.

Second, Viz Media lost localization rights due to a lawsuit between series creator Makoto Raiku and parent company Shogakukan, leaving the manga and anime left unfinished for English audiences. Out of 104 localized episodes, Toonami would drop the series in 2007 after airing only 77. Nonetheless, the series remains one of the most interesting (and underrated) ’00s shōnen anime.

Rave Master

Hiro Mashima has earned a major presence in the anime world thanks to the enormous success of his manga Fairy Tail, but his earlier work Rave Master was surprisingly strong, and its anime adaptation holds up to this day. For a point of reference, Rave Master can be likened to Black Clover in some key ways: the story of a relative nobody named Haru Glory, thrust into circumstances way bigger than himself.

At the same time, it also carries Fairy Tail‘s classic hallmarks (some fanservice, a touch of power-of-friendship here and there), but it’s also enjoyable for the same reasons. The heart and fun of Fairy Tail is present in Rave Master in spades; in fact, Rave Master arguably does Fairy Tail‘s tropes better. There’s one major caveat, though: Rave Master‘s adaptation was cut short, only covering 12 volumes of the 35-volume manga, an unfortunate fate for such a promising series.

Shenmue: The Animation

The Shenmue franchise is practically gaming royalty, and its entries are considered some of the most immersive open-world games around. Its vivid world is anchored by Ryo Hazuki’s quest to master martial arts and avenge his father’s death—a seemingly simple premise that blossoms into a vibrant web of mysteries, criminal underbellies, and the supernatural. Between its rich settings, narrative, and action, Shenmue was a shoo-in for an eventual anime adaptation.

Needless to say, fans were elated when that adaptation finally came in 2022, co-produced by Crunchyroll and Adult Swim. Unfortunately, the series would be canceled after its first season, possibly due to cuts following Warner Discovery’s merger. With the first season still focused on Ryo’s investigations into his father’s killer, there was so much left to explore after its tantalizing first season.

Bobobo-bo Bo-bobo

Bobobo-bo Bo-bobo is an incredibly funny, weird anime that existed as a loving parody of the shōnen genre itself. It abounds with self-referential gags and lampoons shōnen clichés, with titular protagonist Bo-bobo himself parodying Fist of the North Star‘s Kenshiro. In a world where the Maruhage Empire wants to do away with hair entirely and shave everybody bald, Bo-bobo is a rebel fighting back—with his signature “Super Fist of the Nose Hair”, no less.

Although Bobobo-bo Bo-bobo is a hilarious, crude, and deeply unpredictable show, its characters are bizarrely lovable. This adds insult to injury when, after 76 episodes, the series was abruptly canceled—something the show parodies itself with a comically fourth-wall breaking last episode—right as all nine of its central characters start coming together. The following arc would have been fantastic, but unfortunately, it’s unlikely to ever see the light of day in an anime adaptation.

Astro Boy

Osamu Tezuka’s Astro Boy is the most influential manga of all time, and it wouldn’t be an overstatement to say it’s largely responsible for the modern anime and manga industry. Its 1963 anime adaptation would be the first weekly anime series to cross over to America. Alongside contemporaries like Speed Racer, Astro Boy would play a major part in introducing Western audiences to anime altogether.

There’s a certain irony, then, that when the anime’s 2003 remake premiered on Toonami in 2004, it would effectively bomb. Despite being fully completed with 50 episodes total, due to poor ratings, only 15 episodes would ever be broadcast on Toonami. It’s hard to say exactly why Astro Boy failed—perhaps it was due to localization, its idiosyncratic character design, or modern audiences’ lack of familiarity with the character.

But in hindsight, 2003’s Astro Boy remains an enjoyable watch, especially with the original Japanese audio and score. It’s also an example of how even when Cartoon Network airs a genuinely good anime with a sterling pedigree, its success can’t ever be certain.