The Final Fantasy series is synonymous with the Japanese role-playing game genre. Soon to be 16 entries deep, with nearly countless side entries, the series has inspired so many game creators and it still continues to innovate and shine amongst its peers.

No matter how many iterations and gameplay changes that Final Fantasy has gone through over the years, something that has never completely fallen to the wayside is the immense challenge. Every single game is filled with bosses that aim to make all of the progress you have made feel like it amounted to nothing. With decades worth of genre-defining classics, there has been a fair share of bosses that have tormented players both new and old.

10 Long Gui (Final Fantasy 13)

One of the most controversial entries in the series, Final Fantasy 13 was praised for certain aspects of its battle system and its story and characters, but was criticized for removing a lot of exploration in place of linear hallway-style level design. The one portion of the game that lets players fully explore is filled with high-level enemies, with the Long Gui always looming in the distance. This beast has enormous health levels, far beyond mostly all of the story bosses, and if beginner players aren’t careful, they will walk right into a death trap.

9 Ozma (Final Fantasy 9)

While this boss may not look like much more than a floating orb, Ozma is not to be trifled with. It takes the form of a focused ball of energy, with its true Eidolon form being lost to history. To reach this boss, players need to spend a lot of time in the Chocobo Hot and Cold mini-game, and Ozma will eventually present itself. Ozma’s attacks are quite unpredictable and have sent players into a frenzy trying to come up with strategies to defeat the strange ethereal being.

8 Warmech (Final Fantasy)

Going back to the very beginning, the first Final Fantasy didn’t pull any punches when it came to being difficult right out of the gate. The secret Warmech boss appears by chance, and can take new players totally off guard with its intense attacks and healing abilities.

In certain versions of the game, Warmech is even stronger than the final boss of the game, which shows that it is not to be underestimated.

7 Kefka (Final Fantasy 6)

Final Fantasy 6 is home to one of the most emotionally intense stories of the series, and Kefka is a huge part of that. No spoilers, but Kefka is an incredibly important villain in the series and one that has achieved things that few others have. With that amount of distinction, Kefka just had to be an enormous challenge when his boss fight rears its head. This fight against this towering ethereal form of Kefka will take everything the player has, and is incredibly satisfying when overcome.

6 Yunalesca (Final Fantasy 10)

Within a game that has many infamously difficult bosses, Yunalesca stands tall and terrifying. This slithering nightmare beast will take some time to conquer, because of its many variations of creative strategies to down your team. If players can stand this increasingly intense endurance round, you will be rewarded handsomely. But be careful, Yunalesca doesn’t play around.

5 Altima (Final Fantasy Tactics)

In this spinoff title, the final boss Altima provides the perfect final challenge for your team. Her Ultima Demons are the main source of difficulty, due to their immense power and their ability to wipe out your entire team in the blink of an eye. In order to complete the journey, you’ll have to pull together and figure out a way to defeat the harrowing leader of the Lucavi Demons.

4 Emerald Weapon (Final Fantasy 7)

One of the most infamous titles in the series is also home to many secret non-story bosses that will test all of your skills.

Emerald Weapon is one of the most dangerous bosses in the game: it must be found and chased down and once you engage it in battle, a timer is put in play. A major strategy is necessary to overcome this mechanical menace; no blind attacks here.

3 Yiazmat (Final Fantasy 12)

This secret boss from Final Fantasy 12 is no laughing matter. Yiazmat has 50 million HP and takes a very long time to defeat, all the while the player must keep their defenses up and their attacks plentiful. Yiazmat has the most health of any Final Fantasy boss thus far, so any adventurer should be wary before taking this challenge. Its bizarre shape and imposing presence will steer most players away.

2 Hades (Final Fantasy 9)

Originally aimed to be the final boss of the game, Hades is an absolute powerhouse. Magic is the name of the game, as Hades will use every spell in the book to inflict ailments on your team and attack them directly. Most bosses are original creations for the game, but it’s quite a shocking revelation when you find Hades, the lord of the underworld, is a secret boss in the game. Best of luck adventurers.

1 Absolute Virtue (Final Fantasy 11)

One of the MMORPG entries in the Final Fantasy series, 11 still had its share of insurmountable boss fights. Absolute Virtue is an enormous superboss that was infamous in the game’s community for how ridiculously hard it was. Players needed to spend a lot of time grinding and completing missions to build up their characters, as well as creating strategies for this beast. It was nerfed after release, but still poses one of the greatest threats in the series.

NEXT: Final Fantasy XIV: 10 Worst Dungeons, Ranked