Rudbornn Chelute

is an Arrancar in Aizen's army, and the sole member and founder of the Exequias

Character outline
Unlike most Arrancar, his face is hidden. He is distinguished from the other Exequias with his bull-shaped skull, instead of the typical human-shaped skulls his subordinates wear. He seems to know Dordonii. It is unknown when Rudobōn joined Aizen's army, but he implied that his powers were given to him by Aizen, meaning they have some history.

Hueco Mundo Arc
He and his subordinates clean up after each battle, collecting data before killing any survivors: it is implied they killed Dordonii and Cirucci Thunderwitch off screen for failing to win against their opponents, and prepared to do the same with Chad and Gantenbainne Mosqueda before being approached by Retsu Unohana and Isane Kotetsu. Surprised by the arrival of a captain-level Shinigami, Rudobon and the rest of the Exequias withdraw in order to avoid conflict.

Fake Karakura Arc
He and the rest of the Exequias appear in front of Ichigo in order to prevent him from reaching Ulquiorra and Orihime however, Ichigo's friends engage the Exequias in order to allow Ichigo safe passage. Rudobōn told the others not to let themselves be distracted by this though and made his way to his target before being halted by Rukia, who caught his sword and hand in ice. Soon after, he is able to break the ice fairly easily. Later it is shown that Rukia has defeated all of his underlings, leaving Rudobon only to say she will soon learn that defeating his underlings won't bring her to victory. He then releases his zanpakuto, Árbola.

As his fight with Rukia continues, he taunts her as she appears to be at a difficulty fighting against his numerous Calaberas. He then proceeds to lament at how despite his power, he could not make the level of an Espada, and that Rukia and her allies could never match them, for they are just 'birds against a shield'. The battle between them is momentarily halted, as Rudobōn notices that Ulquiorra Cifer has gone through the dome of Las Noches. Seeing this as an opening, Rukia then freezes his "branches" saying "you shouldn't have shown me your power". Then a much bigger Yammy fell, attacking Rudobōn. His current fate is unknown.

Zanpakutō
. In its sealed state it looks like a standard Katana, albeit longer and thinner. Árbol did not show any individuality or unique abilities, like most of the Privaron Espada, or some Espada, in it's sealed form.
 * Resurrección Its release command is . In his released state, the right side of Rudobōn's body becomes wrapped in branches reaching down to his waist, where they split off into roots that flare out on either of Rudobōn's sides. Four lightning bolt shaped branches grow out of the upper part of his right arm, with skulls similar to those worn by his subordinates hanging off of each one. He also carries a lightning bolt shaped stick or branch. He can grow six more of these branches (totaling ten) that spread to the other side of his body.
 * Resurrección Special Ability: From the skulls he can generate an unlimited amount of, his subordinates. This appears to be the reason why the rest of the Exequias all have the same mask. This also means that the Exequias in truth is Rudobōn alone. He refers to this ability as "godlike" and mentions that it was given to him by Aizen.

Trivia

 * He and his subordinates have no visible signs of flesh on their body as they are covered from hem to toe in Arrancar garb, with their respective masks.
 * Rudobōn is one of the few Arrancar to retain a type of weapon after his Resurrección, in the form of a sharp staff. He shares this trait with Mila-Rose, Neliel Tu Oderschvank, Nnoitra Jiruga, Aaroniero Arruruerie, Halibel and Ulquiorra Cifer.