The Grand Betrayal
Bleach: Soul Society Infiltration (Vol. 20) (2005)
Writer/Artist: Tite Kubo | Format: Manga Volume 20
Aizen fakes his death, reveals his villainous godhood on Sokyoku Hill, and ascends to Hueco Mundo.
Why Start Here: The greatest plot twist in modern shonen anime history.
The Transcendent God
Bleach: Deicide Arc (Vol. 48) (2010)
Writer/Artist: Tite Kubo | Format: Manga Volume 48
Aizen evolves through the Hogyoku into a butterfly-winged god, facing Ichigo Kurosaki's Final Getsuga Tensho.
Why Start Here: The climactic battle showcasing Aizen's reality-shattering immortal forms.
Chair-Sama in the Blood War
Bleach: Thousand-Year Blood War (Vol. 74) (2016)
Writer/Artist: Tite Kubo | Format: Manga Volume 74
Even bound to the Central 46 muken chair, Aizen assists Ichigo against the almighty Yhwach using Kyoka Suigetsu.
Why Start Here: Legendary climax where Aizen deceives the god of the future.