Bleach stars many destructive villains in its long run. During the Hueco Mundo story arc and the fake Karakura Town arc, the ten Espadas served as some of the most powerful and terrifying antagonists of all. They are the ten strongest Arrancars, each one being a Menos Grande with unique abilities and outlooks on life.
Ichigo Kurasaki went up against several of these mighty foes during the story, as did the Captains of the Soul Society. As Baraggan Louisenbairn explained, the ten current Espadas each embody a different aspect of death, making them some of the most thematic Hollows in existence. After all, Hollows are cursed and bitter beings bound by restless undeath, each one representing a different reason why people die.
Yammy Llargo: Death By Rage
Bleach's 10th Espada is Yammy Llargo, though his rank changes to 0 when he releases his zanpakuto, Ira. Yammy is a brute-force fighter who loses his temper easily, actually drawing strength from rage and fury. In his released state, he becomes a giant who grows tougher and stronger as his anger heats up. As far as Sosuke Aizen is concerned, there is no limit to Yammy's wrath and power. Any being who realizes they died unfairly must be furious about the life that was stolen from them, and will take out their anger on other spirits once they mutate into a Hollow. It's an eternity of frustration and rage.
Aaroniero Arruruerie: The Gluttonous Greed
Many Espadas' aspects of death may be represented by a Hollow before and after that person died. Someone may be incredibly greedy or gluttonous in life, recklessly seizing everything they want as if by compulsion or extreme hunger. But not even a vast collection of wealth or expensive foods can hold off death forever, and none of these treasures carry over to the afterlife in the sands of Hueco Mundo.
Aaroniero Arruruerie, a mere Gillian-class Menos, started over by devouring an incredible 33,650 Hollows, allowing him to amass enough power to rank among the ten Espadas. This didn't save him from Rukai's icy blade, though.
Szayelaporro Granz: The Delusion Of Grandeur
Bleach's 8th Espada is Szayelaporro Granz, who tried in vain to become the ultimate being via mad science. He desired immortality and being free of the fear of death, but such perfection is fundamentally impossible -- even if it happened, it would be a dead end leading to despair. Since they are no longer struggling to improve and keep pace with the world around them, the person would effectively die inside.
Searching for immortality in life is a doomed quest, and even as a Menos, seeking perfection is a fool's game, but Szayelaporro never realized that. And he paid the ultimate price for it.
Zommari Rureaux: Intoxication/Hedonism
Zommari Rureaux, the 7th Espada, got drunk on his own power, leading to his downfall when he faced Byakuya Kuchiki late in the Hueco Mundo story arc. Zommari appears to be pious and monk-like at first, but in reality he fancied himself the king of all creation, since his released form, Brujeria, allows him to control other people. He believes all things are in his dominion and reveled in this power -- leaving himself critically vulnerable.
In life, a person can easily get themselves killed thinking they are invincible or above the rules, and a Hollow with a similar attitude will soon be gobbled up. What Zommari needed was humility to temper his tragic arrogance, but he never obtained it.
Grimmjow Jeagerjaquez: The Emptiness Of Destruction
One of Bleach's first and most exciting Espadas to appear was Grimmjow, who soon became Ichigo's bitter rival. Grimmjow's aspect of death is destruction, mirroring his bloody quest to become Hueco Mundo's king and apex predator. Grimmjow longed to be the best and had the sensibilities of a wild animal: the strong conquer the weak in a vicious food chain, while instinct is superior to man's feeble laws, morals or philosophies.
But while he did prove himself an excellent predator, it was all for nothing. He kept killing and destroying everything in his way, only to remain the same lonely, bitter being he always was. Ichigo wondered what Grimmjow was supposed to do with himself when surrounded by nothing but the corpses of his enemies, all alone. Grimmjow has no answer for that.
Nnoitra Gilga: Terror In The Face Of Despair
Nnoitra the 5th Espada's aspect of death, despair, is mostly projected onto others. Like Grimmjow, Nnoitra seeks to become the ultimate fighter whom everyone else respects and fears, having ultra-hard hierro skin and sharp instincts on his side. Most opponents soon give in to despair as they struggle in vain to take Nnoitra down. Sure enough, Ichigo and his new ally Nelliel felt utter despair when Nnoitra cornered them.
However, it may be Nnoitra who feels the ultimate despair, for the same reasons as Grimmjow. No matter how powerful or famous he becomes, he is still a Hollow, a cursed and empty being with no hope of salvation. Nnoitra understands this, but that doesn't make him feel any better.
Ulquiorra Cifer: The Persistence Of Nihilism
Given enough time, any Hollow or Arrancar may give in to nihilism, the belief that there is ultimately no meaning or point in anything at all. Nihilists such as Ulquiorra, the 4th Espada, scorn others for imagining meaning or purpose to the people or things around them. Aren't those values just desperate delusions to hold off the despair of nothingness?
Ulquiorra is positive that if his eyes cannot perceive something, then it is not real, and he tried to force this view onto his captive Orihime. When Orihime insisted that the intangible "heart" between friends gave them strength and hope, Ulquiorra scoffed -- until he was seconds away from death. His final act was to reach out to Orihime, desperate to see that wonderful "heart" of hers, only to fade away.
Tier Harribel: The Price Of Sacrifice
Not all Hollows are as self-absorbed as Grimmjow or as nihilistic as Ulquiorra. Tier Harribel, the 3rd Espada and future queen of Hueco Mundo, was the opposite. She lived primarily for the sake of others. At one point, this massively powerful Vasto Lorde happened across three weak Gillians -- Emilou Apacci, Sung-Sun and Mila Rose -- who needed help, and the four of them soon became good friends.
From firefighters to soldiers, a person may give their very life for the sake of others, and as an Espada, Harribel is ready to lay down her life for the sake of innocent Hollows who need her. She fought Hitsugaya not out of wrath, but to avenge her fellows.
Baraggan Louisenbairn: The Inevitability Of Time
Perhaps the most thematic Espada of all is the 2nd -- Baraggan Louisenbairn, the fallen king of Hueco Mundo. This mighty Vasto Lorde has the incredible ability to rapidly age and rot away anything that gets too close, from flesh and bone to kido spells and even stone.
All things crumble to dust or decay over time, and nothing is free from the inevitable flow toward the future. Baraggan embodies this in philosophy and power alike, and very nearly killed Captain Soi Fon and Hachigen Ushoda until the latter turned Baraggan's own power against him. Despite his boasting, Baraggan was simply another creature that feared death.
Coyote Starrk: Isolation Can Kill
Bleach's Primera Espada, Coyote Starrk, was too powerful for his own good. As a Hollow, his aura was so strong that he accidentally killed everything that got too close, and his strength led to bitter loneliness. So Starrk split into two beings, with his friend Lilynette Gingerbuck keeping him company.
Later, as the Primera Espada, Starrk faced multiple opponents alone in his released form. While he fought well, no one came to his aid -- least of all Sosuke Aizen -- and Stark died a lonely death. His lethal power caused loneliness before, and in its own way, that loneliness eventually killed him.