Baraggan Louisenbarn is a prominent antagonist in the anime Bleach, recognized as the former ruler of Hueco Mundo who later became the Segunda Espada, holding the rank of number two within Sosuke Aizen's army of elite Arrancar. He represents the aspect of death by aging, a theme that permeates his very being and abilities. His physical form is that of an immensely tall, muscular, yet elderly man, which distinguishes him as the oldest-looking among the Espada. He has grey hair, a large white mustache, and prominent scars, including one over his right eye. The remnants of his Hollow mask take the distinctive shape of a five-pointed crown atop his head, a clear symbol of his former royal status. He typically wears regal attire, including a white leather coat and a large golden wristband, and carries a large, double-headed battle axe named Arrogante.

Prior to Aizen's arrival in Hueco Mundo, Baraggan was the undisputed God-King of the desolate realm, reigning over his Hollow subjects from the original Las Noches, which was then an open-air palace. He had grown immensely bored from having nothing left to conquer or any worthy opponents to fight. This monotonous reign ended when Aizen, along with Gin Ichimaru and Kaname Tosen, invaded his throne room. After Aizen used the hypnosis of his Zanpakuto, Kyoka Suigetsu, to instantly slaughter Baraggan's entire army in what appeared to be a single moment, the King was forced into submission. Although he was incorporated into the Arrancar army as the Segunda Espada, he was never truly loyal, harboring an intense and burning grudge against Aizen for usurping his throne and humiliating him.

Baraggan's personality is defined by his immense pride, arrogance, and regal authority. He carries himself as an emperor and demands to be treated as such, with his Fraccion addressing him as Your Majesty. He views almost all others, including his fellow high-ranking Espada like Coyote Starrk and Tier Harribel, as beneath him, often dismissing them as ants or worthless. He is cold, calculating, and patient, preferring to slowly and methodically torment his opponents rather than grant them a swift death. This demeanor stems from his deep-seated belief that his power, which governs the inevitable process of aging, is the most absolute and supreme form of death. He detests his subordinate position to Aizen and does not hesitate to openly criticize him or assume command whenever the opportunity arises, as seen during the battle for Karakura Town.

In the story, Baraggan plays a major role during the Fake Karakura Town arc. When Aizen is temporarily sealed by Captain-Commander Yamamoto, Baraggan seizes command of the Arrancar forces. He demonstrates his strategic mind by identifying the four pillars sustaining the fake town and sending his Fraccion to destroy them. After his subordinates are defeated, he personally enters the fight against the Gotei 13, specifically taking on Soi Fon, the captain of the Second Division, and her lieutenant, Marechiyo Omaeda. He effortlessly overpowers them using his aging abilities, forcing Soi Fon to use her Bankai, which also proves ineffective against his power.

His key relationships are largely defined by his ego. He holds an intense hatred for Sosuke Aizen, viewing him as a usurper and vowing to make him pay for stealing his kingdom. Despite this animosity, he grudgingly acknowledges Aizen as the Boss due to his superior power. He has a relationship of disdain with his fellow Espada, Starrk and Harribel, whom he considers unworthy of their ranks. Conversely, his own Fraccion, including Ggio Vega and others, are fiercely loyal to him, demonstrating the genuine respect and fear he commands as a former king. He also had a past encounter with a younger Tier Harribel, whom he repeatedly asked to become his subordinate, an offer she refused, leading to a lasting grudge.

Throughout the battle, Baraggan shows little character development, remaining a static figure of tyrannical pride. He is utterly convinced of his own invincibility, and even when he is injured, his rage only serves to reinforce his megalomaniacal claims of being the one true god of Hueco Mundo. His eventual death is not the result of a change in his character but rather an ironic twist of fate that exploits the absolute nature of his own power. His final act is a desperate, futile attempt to throw his axe at Aizen, a final gesture of rebellion against the one who dethroned him, solidifying his role as a fallen king who could never accept his loss of sovereignty.

Baraggan's notable abilities are centered on his dominion over time and aging. His primary ability is Senescencia, which allows him to dramatically slow the speed of any object or attack that approaches him, making it nearly impossible for enemies to land a direct hit. Conversely, by touching an opponent, he can accelerate the aging of their body, such as when he aged Soi Fon's arm to the point that its bones became brittle and broke on their own. His true power is unleashed upon using his Resurrección, activated with the command Rot, Arrogante. In this form, called Arrogante, he becomes a skeletal, Grim Reaper-like figure draped in regal cloaks. His Senescencia becomes a passive, short-range aura that ages and disintegrates anything it touches, including the ground he walks on. His most devastating technique is Respira, a cloud of dark, miasmic energy that radiates from his body. Respira rapidly ages and rots anything it comes into contact with, including living flesh, inanimate objects, and even energy-based attacks like Kidō, as all things created by living beings are subject to decay. This ability is so absolute that it can only be countered by being teleported inside the user himself, which is precisely how Baraggan meets his end when the Visored Hachigen Ushoda teleports his own decaying arm into the Espada's body, causing him to be consumed by his own inexorable power.