Best Secret Bosses in the Kingdom Hearts SeriesThe Kingdom Hearts series is known for it's intensely difficult optional/secret bosses, they are also generally the best bosses in the series. This list will include optional bosses as well as secret ones.
The Top Ten
This is one of my favourite boss fights in any game, it combines basically every mechanic in KH and then ups the intensity tenfold. This boss is so tough that it can beat you in a literal 10 seconds on the maximum level. - kempokid
The extra boss added to final mix is also really difficult, but I really enjoy it. It's a much more agile boss than most in the game, yet doesn't feel unfair at any point. - kempokid
The Sephiroths in both games are really well made, but I prefer the one in the second game just because I find him more fun. The strategy of using retaliating slash is really funny as it absolutely destroys him, but the fight is tough regardless
I love how unique this battle is, having to reactivate your commands in such a way was a great idea, I also like the whole thing about him being all powerful in his book, but being pathetic in the outside world. - kempokid
I find him to be a nice bonus boss that tested my skills really well. His attacks were generally cool and there were enough ways to beat him to make him a fair fight.
Exellent boss design in every way, moveset, mechanics, looks, easily the best out of the organization members and the series
I find the mechanic of the number above your head to be really unique and fun, as it gives the possibility of an overly aggressive boss without being unfair. - kempokid
The first of the bosses to mess with your command bar, and still a great one. The focus on switching between magic and physical was really nicely executed as well. - kempokid
I didn't expect to find a hidden boss in the extra chapter, but I found it an amazing way to end this game, it was tough, cool looking, and unexpected. - kempokid
A fast, fun fight that had the interesting mechanic of clones, where you could combine them if you attacked both at once. A more standard fight, but fun nonetheless - kempokid
This one was ok, but I found balloonra to do way too much damage for him to be a significant challenge. His moveset was more standard than most secret bosses as well. - kempokid