The Espada (十刃, (エスパーダ), Esupāda; Spanish for "Sword", Japanese for "Ten Blades") are the top-ranked Arrancar in Sosuke Aizen's army of Hollow-Shinigami hybrids, are the most powerful Hollows under Aizen's command, and are the main rivals of the Gotei 13.

Those among the Arrancar that excel in killing power are chosen and favored according to their strength are assigned a number from one to ten, collectively referred to as the Espada, holding absolute power and authority over the Números.  At any given time, the Espada has a nominal composition of ten members, all hand-picked and ranked by Aizen himself. Along with Aizen, Gin Ichimaru, and Kaname Tosen, the Espada as a group possess comparable strength to Soul Society's Gotei 13 Shinigami captains.

At the time of the group's introduction, the Espada consists of nine males and one female. Each Espada member is chosen for their superior combat ability and then assigned a number from 0 to 9 (0 being the strongest), originally thought to be ranged from 1 to 10, that indicates their rank and relative power level, which is tattooed somewhere on their body. For instance, Grimmjow Jaegerjaquez's is located on the right side of his lower back and Coyote Starrk's is on the back of his left hand.

The Espada are given free control over the Números and may choose as many of them as they like to become their Fraccion. Similar to the power gap between captains and lieutenants in the Gotei 13, the strength of the Espada far surpasses that of the average Número. Aizen himself is confident enough of his Espada's abilities to send them out on potentially hazardous missions, such as gathering information in the real world, fighting Shinigami captains inside Las Noches and Karakura Town by themselves, and searching for the Vasto Lorde.