Cero

Cero is a strong and swift spirit energy-based attack used by upper-level Hollows, Arrancars, and Vizards.

Description
is a form of attack used by Menos, Arrancar and Vizard. 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.

The power of the cero is dependant 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.

Cero Doble
Cero doble, Spanish for "double zero" is a variation performed by Neliel Tu Oderschvank, by swallowing her opponent's Cero and returning it back to the user along with her own cero. This attack was first seeing used against Nnoitra Jiruga.

While in her child form, Nel is only able to return the Cero fired by her opponent as seen used against Dordonii Alessandro Del Socacchio.

Cero Sincrético
is a variation performed by Dondochakka Bilstin and Pesche Guatiche. This attack was first seen being used against Szayel Aporro Granz.

Beautiful Charlotte Cuuhlhourne's Final Holy Wonderful Pretty Super Magnum Sexy Sexy Glamourous Cero
This variation is performed by Charlotte Cuuhlhourne. Despite having a very long name and the shape of a heart, it is just an ordinary Cero as noted by Yumichika Ayasegawa.

Gran Rey Cero
is an Espada-exclusive Cero. It is performed by mixing an Arrancar's own blood with the Cero. The result is a Cero with a much greater attack power and speed, as well as a change of color unique to the Espada. This attack was first used by Grimmjow Jeagerjaques in order to incite Ichigo Kurosaki into donning his mask.

Others
While most Cero are red, Ichigo's Hollow form's Cero is tri-focused and pink. The Espada appear to have great color variations in their Cero. Ulquiorra Schiffer's is green, Nnoitra Jiruga's is golden yellow, Nel Tu's seems to be violet (as she was using Cero Doble, it is unclear if her normal Cero is a different color), and Grimmjow Jeagerjaques's is blue.