Cero (虚閃 (セロ), sero; Spanish for "Zero", Japanese for "Hollow Flash") is a form of attack used by Menos, Arrancar and Vizard. Basically an energy blast, it consists of firing a blast of concentrated spirit energy at the target. While in most cases it is fired from the mouth, some Arrancar and Vizard are capable of firing Cero from their hands, fingers and other parts of their bodies. This often requires the user to under take a specific pose, with the former First Espada, Coyote Starrk, being the only exception.
The power, force, speed, and blast area of the Cero is dependent on the strength of the user (i.e., the stronger the user, the stronger the attack), and there are some Arrancar and Vizard who have come up with their own variation.