There are all kinds of scary villains in Tite Kubo's hit anime series Bleach, and some of the battles against them are real nail-biters. While Sosuke Aizen is the ultimate villain for most of the narrative, and Yhwach dominates the Thousand Year Blood War arc, some of the top Espadas are terrifying monsters in their own right.
This includes the Segunda Espada, Barragan Luisenbarn. He once reigned as Hueco Mundo's king, and his hollow powers are simply incredible. In his sealed arrancar form, he emits a death aura that dissolves anything which comes too close. And his released form expands that aura further, while also granting him a ranged "death breath" attack and a massive double-sided ax called Gran Caida ("great fall"). He's a juggernaut villain who can crush almost anyone, but not quite. Who are five tough warriors Barragan could grind under his heel, and who are five other characters who would dethrone the king of Hueco Mundo in battle?
10 Can Defeat: Ichigo Kurosaki
That's right, not even the hero himself could handle Barragan in a straight-up fight, at least not as of the Fake Karakura Town arc. Ichigo's potential is nearly limitless, due to his inner power and all the training he gets. But he often needs help vanquishing the big bad guys, and Barragan is already ready to fight.
In a battle, Ichigo might strike even against the Segunda Espada's sealed form, but once Arrogante (his release) comes out, forget it. Ichigo would either flee, or get caught in a death breath attack and dissolve to dust. Ichigo did have that super inner hollow to beat Ulquiorra with, but we bet that Barragan would dissolve it before Ichigo could use it.
9 Can't Defeat: Sosuke Aizen
Barragan is scary, and he ranks near the top of the Espadas. But he couldn't best his boss in a duel, whatever his grudge might be. Aizen is faster than anyone else, and his kido is on a whole different level. Barragan can rot energy attacks that get close, but he can't dissolve everything at once. Something will get through.
And of course, Aizen's shikai, Kyoka Suigetsu, would spell Barragan's doom, should it be used. With those illusions, Aizen could fool the Espada into thinking he released Arrogante, while he's really just standing there. Then Aizen could cut him down with a mighty strike.
8 Can Defeat: Byakuya Kuchiki
Byakuya knows his stuff, but he never went up against a villain like this. What can the 6th Captain do? He's got first-rate shunpo, a variety of kido that he can use without the incantation, extreme sword skills, and a shikai and bankai based on swarms of sharp petals.
All this would do some damage to the Segunda Espada, such as the Throat Scene bankai attack that was used on Zommari. But that's as far as Byakuya can go. Barragan will survive that by rotting away the bulk of Byakuya's attack, then radiate so much death breath that Captain Kuchiki would find himself dissolved to the bone.
7 Can't Defeat: Ulquiorra Schiffer
Okay, this one is tricky to figure out, since no one seems to know Ulquiorra's true potential. Why is that? Ulquiorra's terrifying Segunda Etapa is top secret, something that not even Aizen himself has seen. Most likely, that form didn't factor into Ulquiorra's Espada rank, so he's stronger than his "4" rank suggests.
It took Ichigo's godlike inner hollow to defeat him, and even then, Ulquiorra did some damage. This bat-like Espada boasts dizzying speed, crushing strength, great reflexes, an aptitude with the Cero Oscura, and mega-powerful lightning spears. If Ulquiorra kept moving and launched enough of these attacks, he could wear down Barragan's defenses and deal the finishing blow. It would be tough, though, given how effective Barragan's rot-based powers are. Ulquiorra would barely limp away from this one.
6 Can Defeat: Nnoitora Gilga
Here's another Espada that ranks below Barragan: the Quinta Espada, Nnoitora Gilga. He's a lot like Grimmjow, favoring up-front melee attacks and some bone-splitting strength to win the day. He dealt some serious injuries even to the likes of Kenpachi before he finally went down. Don't forget his hierro armor skin, the toughest among all Espadas.
All of this gives Nnoitora some impressive endurance when fighting Barragan, and in their sealed forms, they probably strike even. But once Arrogante comes out, Nnoitora is doomed. Death breath, Gran Caida, and maybe a Gran Rey Cero are all that Barragan would need to finish off his six-armed opponent for good.
5 Can't Defeat: Genryusai Yamamoto
It's the Head Captain himself, Yamamoto! No matter how powerful you are, this old man will demand your utmost attention. He's the most powerful Soul Reaper born in a millennium, and his flame-based powers have the power to destroy the entire Soul Society.
His shikai, Ryujin Jakka, is already enough to shape an entire battlefield according to his will, and his bankai, Zanka no Tachi, is out of this world. It's a heated blade that vaporizes anything it touches, and it has a special attack for each cardinal direction. Barragan's rot powers and cero blasts would give Yamamoto a hard time, but surely, Yamamoto's flame powers would overwhelm Barragan's defenses and reduce this hollow to ashes.
4 Can Defeat: Soi Fon
Here is another Soul Reaper Captain who, while an impressive fighter, isn't ready for Barragan's might. She really did face him in the anime, and the entire time, Barragan had the upper hand. Soi Fon, like her mentor Yoruichi, is an assassin who likes to get up close. Her shikai, Suzumebachi, is a stinger that can kill anyone with two strikes in the same spot.
But as the anime showed, Soi Fon simply can't get close! Barragan's rot powers drove her back several times, and not even the aid of Hachigen's kido castle could allow Soi Fon's bankai to deliver the final blow. Alone, Soi Fon would simply retreat after a point after assessing the situation.
3 Can't Defeat: Yhwach
In a battle of the kings, it is the Quincy, not the arrancar, that will win the day. Yhwach's powers are vast, and he can do things that no other character can even conceive of, let alone try out for themselves. His letter is "A" for "the Almighty," and that name is well earned!
Among other things, Yhwach boasts massive spiritual pressure and speed, a sword, bows and arrows, and even the ability to recall other Quincy powers into himself if need be. And when his Almighty power comes online, he can see infinite futures and even avoid his own death. Barragan is scary, but he can't match that.
2 Can Defeat: Uryu Ishida
Barragan can't take on Yhwach and survive, but he could handle most of the other quincies, such as the mighty Sternritter. This includes Uryu, the teenager who was granted with the letter "A" and named as Yhwach's successor.
Uryu is a smart and talented boy, capable of taking on Captains. But he couldn't even defeat Szayelaporro, let alone someone like Barragan! The Segunda Espada can rot away whatever Uryu throws at him, and a well-aimed Cero Oscuras or death breath attack would turn Uryu to dust.
1 Can't Defeat: Ichibe Hyosube
This bearded man is a member of the legendary Squad 0 of the Soul Society, a squad of five extraordinary Soul Reapers. He is the one who created the names of everything in the Soul Society, and he is ancient and incredibly intelligent.
Not even Barragan is exempt from this astounding power. Ichibe can even bring himself back together upon death if anyone says his name, and should Barragan kill him, Ichibe could trick him into saying his name. Meanwhile, Ichibe can reduce or negate the power of any object or person based on altering their names, and the color black is his domain. And Barragan has an all-black body aside from his head and hands! This Espada is finished.