Herrera Tresckow

Herrera Tresko (トレスコ・ヘレラ; Toresuko Herera) was an arrancar who was a member of Aizen's army, though he secretly plotted to assassinate him. He only had a small band of followers, but his plot failed and Herrera fled into the deserts of Hueco Mundo and remained hidden until Aizen's fall.

Early years
Herrera was an adjuchas-class Menos prior to shinigamification. He was ranked Quinta, Fifth, in the Espada that existed prior to Aizen's arrival in Hueco Mundo. Once Aizen arrived on the scene, Herrera saw the life that he knew fall apart as changes were made, stemming from Aizen, Gin, and Tosen. The arrancar hated them all, especially Aizen. Aizen saw the strength that Herrera had and shinigamified him with the Hogyoku. As with many other arrancars, Herrera failed to defeat Aizen at their first encounter.

Tosen commented that he did not trust Herrera, to which Aizen replied that he had his uses, given the proper motivation.

Assassination plot
Under Aizen, Herrera has been plotting to assassinate Aizen out of simple discontent with his superior. He planned on recruiting Nelliel Tu Odelschwanck and Baraggan Luisenbarn, though his plans were discovered before Herrera could make secret contact with either of them. He was the second-to-last member of the original Espada at the time, leaving Aaroniero Arruruerie. His reason for not approaching Aaroniero was said to be because Herrera did not trust Aaroniero or his potential for omnipotence.

Moments before Herrera fled, he fired a Gran Rey Cero from the entrance of Las Noches, causing structural damage and causing a portion of the palace to crumble.

Personality and traits
Unlike other arrancars, Herrera was moralistic and stubborn about it. He refused to travel to the human world to hunt down spirits to eat and explained himself by saying that they tasted terrible and thus hardly worth the effort. However, Herrera hated how Aizen just "waltzed into [their] den and usurped power."

Powers and abilities
Immerse Spiritual Pressure: From centuries of experience, before Aizen appeared, Herrera was able to manifest himself into a deadly force. Minor hollows trembled before his appearance in the days before Herrera fled into Hueco Mundo's enormous deserts.

Stealth: Herrera has demonstrated the ability to render himself invisible or camouflage himself to hide from his opponents. Combined with his high degree of control over his reiatsu, Herrera could hide himself from even captain-level shinigami. He, presumably, used this power to great effect in order to remain hidden throughout Aizen's reign.

Cero: As with most arrancars, Herrera has shown the ability to use cero. Herrera has demonstrated the ability to fire powerful ceros without having to charge it up, making the usage of bala almost obselete.
 * Gran Rey Cero: Moments before he made his escape, Herrera defiantly fired a Gran Rey Cero within Las Noches, causing enormous structural damage. He stated that the cero would have obliterated the building if he had the time to charge the cero to cause more devastation, though doubtful that it would have caused anything more than injury to the building's occupants, anyways.

Hierro: Herrera has a strong hierro, being capable of blocking a multitude of shikai-strength sword strikes with his arm, even hooking his arm around the blade to halt its movement.

Zanpakutō
Herrera's zanpakutō usually is sheathed at his side, resembling typical katana. The hilt features a yellow tassel and the guard consists of four prongs, with the sharp tips facing the same direction as the blade. It is released by the word Break (破る; yaburu). Although briefly seen, its name or abilities remain to be known.

Behind the scenes
Herrera was designed to go against the evil archetype that is present in arrancars. He is named after Spanish architect Juan de Herrera and German World War II officer Henning von Tresckow, who headed a coup that almost killed Hitler. The character was designed with the intentions to be an antihero.