Sōsuke Aizen
Arrancar are introduced into "Bleach" following Ichigo's return from Soul Society, serving as major antagonists until their collective defeat in the Fake Karakura Arc. Most of the arrancar antagonists served Sōsuke Aizen, who used an item called the "hōgyoku" to artificially create more arrancar. While more conscious than their original hollow selves, some arrancars are either sadistic psychopaths or display honor or compassion which resulted in some befriending the heroes. The arrancar are first shown scouting Ichigo's hometown by ones and twos, which escalates into sorties, and eventually a battle on earth and in Hueco Mundo between the most powerful arrancar and Soul Reapers. Following Aizen's defeat, the arrancar survivors attempted to become their society before they conquered by the Quincy extremists known as the Wandenreich, with those captured either drafted as expandable foot soldiers or executed as monsters.