Former Captain Sosuke Aizen is the big bad guy of Tite Kubo's popular anime Bleach, and it takes a titanic effort from Ichigo and the Soul Society to defeat him for all time. When we first met him, we saw the polite and soft-spoken Captain Aizen, loved by the entire community. His Lieutenant, Momo Hinamori, saw him as a father figure and would give her life for him.
All of that changed when Sosuke Aizen unveiled himself as the madman who turned the Soul Society upside-down and launched a brutal campaign to rule over all of creation with his arrancar army. Nothing but the sharpest sword will stand between him and total domination. So, what are the 10 most despicable and cruel things Aizen has done on his quest for power? His victims are many...
10 His hollowfication experiments
Chronologically, Aizen's scheming began some 110 years before the main events of Bleach, and we witness all this during the Turn Back the Pendulum arc later in the series. At the time, Aizen and his fellows operated from the shadows, and anyone and everyone was fair game for Aizen's experiments.
Civilians were seemingly evaporating into thin air, and once a squad of Captains and Lieutenants muscled in on the scene, Aizen morphed them into visoreds! Unable to control these powers, the hapless Soul Reapers nearly killed one another until Hachigen and Tessai arrived.
9 Kisuke, the fall guy
Someone was definitely going to notice if a handful of high-ranking Soul Reapers became hollows, and Central 46 demanded answers. But Aizen, along with Gin and Kaname Tosen, melted into the shadows and Kisuke Urahara was left holding the bag, so to speak.
At once, Kisuke was dragged to Central 46 for judgment, and Aizen let it all happen. Not to mention how Tessai was also punished and banished to the living world. Poor Kisuke! It took a noble and selfless act on Yoruichi's part to get him out of that mess in one piece.
8 The Central 46 Slaughter
This massacre did not take place on-screen, but we do see the end results (and how graphic they are). During the Soul Society arc, Captain Hitsugaya realizes that something is terribly wrong with this whole situation, and he begins investigating the seemingly deceased Captain Aizen.
The trail of bread crumbs led to the underground chambers of Central 46, where he and Rangiku found everyone dead! Aizen had not only wiped them out but also used Kyoka Suigetsu to create an illusionary double of them to keep the Soul Society running.
7 Turning on Momo
Remember Momo Hinamori, Aizen's devoted follower? She loved him like a father, and Aizen returned exactly 0% of those feelings. But they were useful to him. Aizen allowed Momo's grief to help convince everyone that he really was dead, and Momo even turned on Hitsugaya (she later regretted it).
Later, when Momo found Aizen alive and well, they embraced... until Aizen impaled her on his zanpakuto, and left her to die! This poor girl experienced nothing but exploitation and deception the entire time and even later on, she still had a hard time watching everyone else try to kill him. Aizen had wormed his way right into her heart and wouldn't let go.
6 Momo vs Hitsugaya... again
Poor Momo can't catch a break, can she? During the final battle over the replica Karakura Town, it looked like the Soul Reapers had cornered Aizen at last, and Hitsugaya delivered the final blow. Everyone cheered, but Ichigo, who wasn't under the effect of Aizen's shikai, could only stare in horror.
Once the illusion was shattered, everyone saw why: Hitsugaya had been deceived into stabbing Momo, and she nearly died. In a fit of rage, Hitsugaya charged at Aizen, only to be cut down.
5 He ditched the Espadas
Aizen went to great lengths to assemble Adjuchas and Vasto Lordes to form the ten Espadas, the most powerful arrancars of all. Some of them really looked up to Aizen, but he really did not care about them at all. During the final battle, the Espadas began to fall short, and Aizen, growing frustrated, turned on them.
Tier Halibel, was still in fighting shape, but an impatient Aizen struck her down and let her fall far to the ground, and she only barely survived. Halibel was possibly the kindest Espada of all, but her faith was not rewarded in the slightest.
4 He usurped Barragan
Okay, to be fair, Barragan Luisenbarn isn't the nicest guy, either. But this mighty hollow did enjoy being Hueco Mundo's king, and it meant everything to him. He had that world united under him, until Aizen came knocking. Aizen (with Gin and Kaname in tow) approached the king hollow, mocked him, then shattered Kyoga Suigetsu to reveal that he'd already slaughtered Barragan's army!
Aizen kicked Barragan right off the throne and took it, and Barragan nursed a serious grudge. Barragan was evil too, but really, he was just doing what was in his nature, and he didn't exactly launch bloody invasions against anyone. But Aizen was ready for war, at Barragan's expense.
3 His god complex
Why is Sosuke Aizen doing what he's doing? It's simple: he feels despair at the fact that no one actively rules over all of creation. It's a great and vacant throne, and Aizen took it upon himself to fill it. Now, was he really acting for the world's benefit, or just satisfying his bottomless lust for power and glory?
We bet it's the latter, and it shows revolting arrogance and vanity for Aizen to declare himself the rightful god to take that throne. Nothing good ever came from such an attitude, either in Bleach or our own world!
2 He sent White into the living world
Much later, in Bleach's manga, we learn about another phase of Aizen's plan. After the creation of the visoreds, but before Ichigo was born, Aizen's experiments had reached a new phase, and he created a hollow known as White. To make a long story short, White went on a rampage, and it bit a teenaged Masaki and started transferring its power into her.
To save her life, the then-Captain Isshin Shiba melded his soul with Masaki's, and that ended his career as a Soul Reaper. That hollow power would later manifest in Ichigo as Zangetsu. But seriously, Aizen let that horrible thing loose, and once it died, Aizen shrugged it off as a failure and wandered off. That's cold!
1 Captured Orihime, the "traitor"
This list isn't ranked in order, but if it were, this would still be close to the top. Orihime Inoue is a kind and good-hearted girl who gained spirit powers, and she fearlessly fights with Ichigo to uphold justice. Aizen sent Ulquiorra to capture her and take her to Las Noches, but not before leaving behind evidence that Orihime had left willingly!
The Soul Society wrote off Orihime as a traitor, but Ichigo wasn't so convinced. He, Chad, and Uryu launched a rescue mission, and eventually recovered her. But it was all just a trap, and they, and four Captains, were sealed off in Hueco Mundo! This made the invasion of the fake Karakura Town easier. Just when you thought the good guys had Aizen cornered...