Anticlimax Boss: Despite all the build up the character had, the Horned King doesn't put up much of a fight before he is sucked into the cauldron: he lunges unarmed at Taran and grabs him, showing no display of powers or fighting abilities whatsoever, and is killed when Taran pushes him in the general direction of the cauldron.
Audience-Alienating Premise: The film's darker story was this for some viewers, having less of Disney's trademark lightheartedness or kid-friendly moments with which to balance it out. Tellingly, it would be years before Disney would try again for an older audience, again to a similarly mixed response.
Bile Fascination: A downplayed example; It has certainly found a respectable fandom in later years, but its status as the black sheep of the Disney Animated Canon continues to draw newcomers who are curious as to how it gained its reputation.
Complete Monster: The Horned King is an evil, sorcerous lich who wants to use the Black Cauldron to conquer the world with his army of the undead, the Cauldron-Born. Stopping at nothing to achieve his goal, he's willing to kill innocents, has his loyal henchmen killed to create more skeleton warriors, and tries to sacrifice his own servant, Creeper, to power the Cauldron. Desiring to be seen as a god-like figure by what's left of the Earth, the Horned King remains one of the darkest villains in a Disney movie to date.
Ensemble Dark Horse: The Horned King. Even if the movie failed at the box office and is one of the lesser known Disney feature films, The Horned King is a cult favorite within the Disney fandom and many times is compared with the likes of Maleficent and Chernabog. He probably would've had a respectable presence in Disney properties if it hadn't been for the movie's poor initial reception. Fans have even demanded Disney to let the Horned King make an appearance in future Kingdom Hearts games. Being played by the late John Hurt probably has quite a bit to do with it.
Evil Is Cool: Again, the Horned King. If there's one part of the film that's well-regarded, or even well-remembered, it's because of him, probably because he's a goddamned horned-skeleton-wizard-king with the voice of John Hurt, and because he's one of the most aggressively un-comedic and ruthless Disney villains of all time.
Family-Unfriendly Aesop: Taran's character arc contains one: Some people just aren't cut out to follow their dreams.
Genre Turning Point: The film was meant to be this for animated Disney movies in general, an attempt to darken and "modernize" the studios feature film output while also proving that Walt Disney's one-vision method of filmmaking was still viable in the 1980s. And it was a turning point... just not in the way that the film makers had hoped; its massive box office failure not only led to a trend of lighter Disney animated films (which culminated with their "true" turning point in 1989, The Little Mermaid), but also ended (most of) Walt Disney's methods as solid company policy in favor of a more "Hollywood" style of movie making (stricter deadlines, tighter budgets, more committee meetings, more executive influence, attempts on franchise integration, etc.).
Germans Love David Hasselhoff: The Horned King has had plenty of attention in Japan. This may have had to do with the extinct attraction in Tokyo Disneyland.
Mickey Mouse on the Game Boy in 1989 has him as the final boss.
Mickey Mouse II on the same system two years later again has him as the final boss. Although both this and the first game replaced him with Witch Hazel when they were converted to the Bugs Bunny Crazy Castle games.
Mickey Mouse III: Dream Balloon in 1992 again puts him as the final boss, only to be replaced by Night Mayor when it was converted to Kid Klown in Night Mayor World.
Finally appeared without alterations in Land of Illusion on the Game Gear and Sega Master System in 1993, except this time colored from older concept art and given the name of "The Phantom." And this was the only time that he appeared in North America and Europe in a Japanese produced game.
Most of the violence and death in the movie (both what was allowed to be shown and what Katzenberg left on the cutting room floor) these days wouldn't be out of place on Cartoon Network's Adventure Time.
The magic sword sounds and glows much like a lightsaber, as well as being able to cut through most anything. The Horned King also has a habit of throttling his underlings when they have failed him. Then Disney acquires the rights to Star Wars...
This wasn't the last Disney work with a lovable, pink pig.
Jerkass Woobie: Creeper is a nasty little sycophant who nearly shoves embers in Hen Wen's face and takes delight in the prospect of Taran being killed in the climax. However, his master often blames him whenever something goes wrong and throttles him, even when it's not his fault (the collapse of the undead army being the most notable example). He dreads having to inform the Horned King of the prisoners' escape, expecting to be choked before they've escaped as shown with the way he clutches his throat in response to Taran breaking the chain of the drawbridge.
Mis-blamed: Gurgi's mannerisms were not, in fact, Disney putting in an obvious Plucky Comic Relief - things like talking in the third-person, speaking in redundant phrases, referring to Taran as a lord, and "Munchies and crunchies" are in fact in the books, and Gurgi still does play somewhat of a comic relief character.
Never Live It Down: The troubled production and ultimate box office failure of the film shook the Walt Disney Company so much that even after the successful revitalization of its animation department in the years that followed, they largely ignored it for the next decade or so and have released virtually no merchandise tied to it; not even of Princess Eilonwy who remains absent from the Disney Princess lineup. It eventually received a full VHS release and later a DVD release thanks to its respectable cult following, but remains one of its least-publicized pictures. Disney made some noise in 2016 about trying a more faithful adaptation of the Prydain novels in live action, but so far it seems stuck in Development Hell, probably due to this reputation, as well as the Prydain series not being very well known, especially compared to Harry Potter or Narnia.
Nightmare Retardant: When the Horned King's eyes suddenly turn red, he looks too cartoonish to be truly menacing.
Creeper, given his tendency to break the mood during some of the Horned King's more genuinely frightening scenes.
For some folks, Taran qualifies as one. Many people find his bragging annoying, and they do not like how he patronizes Eilonwy in a sexist way ("What does a girl know about swords, anyway!?"). Sadly, this is actually fairly accurate to Book!Taran, and losing this arrogance is part of his character arc in the book series, which the cancellation of any sequels prevented being shown.
Towards the book series it was based off of, it reads almost like a shopping list of cliches. Except one has to consider that the series was originally published in the sixties - Taran predates Luke Skywalker in the "Farm-boy turned hero who befriends a princess".
So Okay, It's Average: The wider consensus of the film, which agrees that while it's far from the worst animated movie and actually has a few good points, its story and characters are thoroughly underwhelming with few of the traditional Disney elements to compensate for it.
They Wasted a Perfectly Good Character: The Horned King is held by some to be a genuinely terrifying Disney villain, yet sadly has little to show for this due to his surprisingly easy defeat at Taran's hands. Frank Thomas and Ollie Johnston cited this as one of the film's biggest flaws in their book The Disney Villain, feeling the film presented him in a way that robbed him of mystery and presented him with so much action and close ups, that it made him come off as a villain who was approachable and unpleasant rather than all powerful.
"Typical of the failings, the Horned King, who should have been mysterious, was as ordinary as the leader of a street gang. As Roy Disney said later, their approach was "too literal-minded. He was just a guy." The use of close-ups and too much activity gave the impression that here was a man one could argue with. He should have been as unreachable and intimidating as Chernobog. No one should speak in his presence. The words should wither in one's throat. We should not even know if this evil creature was man, animal or demon. Here was unlimited power on the verge of taking over the world that somehow had to be stopped, and that was the special challenge to the tiny band of characters who carried the hopes of the future on their uncertain shoulders. It seemed an impossible burden for the heroic cast as well as the inexperienced staff of the studio."
Who else is disappointed Taran had to give up the awesome magical sword midway through, instead of maybe using it on The Horned King?
The fact that Eilonwy is called a scullery maid only gets mentioned in passing. In the books though, she really is a princess - kind of. We also never find out why she has that bauble and what it isnote In the books, Eilonwy is a descendant of an ancient line of magic wielders, and the bauble is actually the Golden Pelydryn, an heirloom of her house that can be used to reveal the words in their book of spells. What doesn't help is the last time it's seen is in Morva.
Vindicated by History: Its noticeably darker tone, new animation format, Executive Meddling and a lot of bad luck made 1985 viewers see the film as a train wreck; modern viewers can appreciate it more.
Visual Effects of Awesome: For all its problems, the film's animation stands out as one of its more polished elements and really lends itself on the dark tone and atmosphere of the story.