Ulquiorra Cifer

Ulquiorra Cifer is one of the most iconic antagonists in Bleach.

He is the 4th Espada in Aizen's army of Arrancar, ranked by raw combat power and Reiryoku (spiritual pressure).

Key characteristics:

• Pale skin, jet-black hair with a signature green tear-like mark running down each cheek
• Emotionless, cold, and nihilistic personality — he frequently expresses that "nothingness" (void/emptiness) is the true nature of existence
• Green eyes that become strikingly visible when his helmet-like mask fragment is removed
• Signature ability: Cero Oscuras (a very powerful black Cero)
• Resurrección: Murciélago ("Bat") — transforms him into a bat-like form with enormous black wings, dramatically increased speed, strength, and the devastating technique Lanza del Relámpago (Lance of Lightning)
• Most famous for his intense, philosophical rivalry with Ichigo Kurosaki and his emotionally charged final battle in Hueco Mundo

He's widely regarded as one of the coolest, most memorable, and tragic villains in the series due to his calm demeanor, philosophical outlook, and unforgettable presence.