Aizen was a captain of the Gotei 13. He had taken the hogyoku that was inside of Rukia, then left them, along with Gin and Tosen, going to Heuco Mondo. using the Hogyoku, he had created Arrancars and the Espada. He is the Main Antagonist in the anime 'Bleach'.

Again, was bored, watching bleach, so I made him.
I apologize for anything I misspelled.

I need to fix his hair still...