An Espada is one of the ten strongest arrancar in Hueco Mundo. They can choose any arrancar below them (besides other Espada) to be their fraccion (similar to vice-captain). They were created by aizen and serve under him. They each have their own aspect of death (example: age, loneliness, rage etc.). Each Espada is able to use gran rey cero. The no. 4 and above Espada are not allowed to release their sword within the dome of Las Noches. Because with their spiritual energy, they would destroy Las Noches.