There are two strange things in this world; First, someone considered and managed to make a crossover between Disney and Final Fantasy. Second, it worked. Kingdom Hearts became a prime example that anything can be properly mixed if you know what you are doing, and one of the many highlights this series has to offer is how you can visit Disney worlds and interact with its characters.
With so many original characters and an overly complicated plot, it's necessary to adapt Disney characters accordingly, so they won't just be there for no good reason. With that said, the way some characters and worlds are adapted to fit within the crazy plot is marvelous, giving a bigger development to them.
10 Hercules
Even though only the "third" game discussed the movie's plot, Olympus has been around in almost every game of the series, and Hercules is one of the most recurring Disney characters.
Not just that, but he's extremely well suited to the games' plot, serving as an example of a man who became a true hero and consistently helps Sora and his friends to reach the same goal.
9 Toy Story
It's hard to pick a single character here when all of them and the world was so beautifully adapted. The characters' behaviors, mannerisms, perspectives on the complex story, and overall characteristics are extremely precise compared to their movie counterparts.
It's no surprise that Pixar helped Square Enix with this world to make sure it's faithful, and even going as far as considering the game's canon for the characters.
8 Beast
A Disney character with many moments to shine throughout the series, we met Beast in the first game, where he searches for Belle who got kidnaped, and he protects us a lot in a particular segment of the game where we are vulnerable.
His adaptation continues in the second game, where Beast is wonderfully manipulated by one of the villains, Xaldin, appealing to his insecurities that no one could love a monster like him.
7 Baymax
In an enticing choice, Kingdom Hearts 3 continues the story shown in Big Hero Six rather than retelling it. And by doing so, they also discuss what is considered a living person, a big topic in the series, by having the original Baymax turned into a puppet of darkness.
The story is brutal and heartbreaking, though the ending is wholesome, and gives Big Hero Six a beautiful sequel, despite not being an actual one.
6 Agrabah
It's hard to pick a particular character from this world as well. Aladdin, The Genie, Jasmine, Abu, Jafar, and even Iago all have wonderful portrayals. Aladdin is one of the best party members, and Genie's performance is very reminiscent of the movies as well, keeping it very faithful to how he's supposed to be.
The wackiness of his powers combined with everything going on is very fitting, and even having him as a summon to call upon anytime is amazing. The story of the movies is also well told, with Jafar being a true menacing force.
5 Pete
From 1925, Pete is actually older than Mickey Mouse himself, who debuted only in 1928, which makes Pete the oldest character Disney continues to use. Still, he gained a new light when he was incorporated into Kingdom Hearts as a minor antagonist who makes some trouble and is defeated, very similar to Team Rocket in Pokémon.
He serves Maleficent, and despite not being very bright, he's very loyal to her.
4 Maleficent
Speaking of, one of the greatest villains in Disney history is Maleficent. As her name implies, she's pure evil (or at least as evil as Disney is willing to go) and is very prominent in the series, being the antagonist from most of the first game and antagonizing the heroes sporadically in the sequels.
Though her presence doesn't outshine the original villains of the game, she even helps Sora against Organization 13 at one point - she's basically in it for herself and her goals.
3 Mickey Mouse
The King of Disney, and quite literally everything else, in this case. Mickey is no stranger to appearing in video games, and one of the biggest characters of the company was bound to have his presence.
Here, he is a Keyblade master, mixing the fighting style with acrobatics due to his size, similar to how Yoda fights in Star Wars. Personality-wise, he is as you'd expect; a kind-hearted King who wants to help save the worlds no matter what. Even past versions of him are referenced, such as his first appearance and his time as a musketeer, from different cartoons.
2 Goofy
Our faithful shield master, Goofy has been with us since the very beginning. He's helped us in most fights throughout the series, and despite his name and demeanor, he is likely the smartest of the trio, offering insightful solutions from time to time and noticing things before Sora and Donald do so.
It's hard not to feel bad for him when he is incapacitated in the second game, forcing us to go without him. Though such a character can be a blank state, for there are many versions of him from different cartoons, the way he is adapted is very well written.
1 Donald Duck
Our favorite healer. When he does heal us, that is.
Also along for the ride since the very beginning, Donald Duck is a powerful wizard, perhaps one of the strongest even compared to Square Enix characters, and his temper is pretty much the same from most of his incarnations in the cartoons. Seeing him using magic for combat was a good choice and quite fitting for the game, And his classic dynamic with Goofy only makes both characters shine even brighter.