The Japanese personification of the grim reaper. In Bleach, they wear black kimonos and wield swords as their primary weapons. They exist to protect and act as couriers to the souls of the recently deceased.
Visored: Shinigami that have obtained the powers of Hollows, the opposite of Arrancar.

A spiritual realm that houses the shinigami and the souls they gather. It exists to maintain the balance of souls in both the living and spiritual planes, because the living cannot exist without the dead.
Rukongai: The outer district where souls live upon arrival to the Soul Society.
Seireitei: The center of the Soul Society, where the shinigami live.
Central 46: The judiciary authority of the Soul Society, comprised of 40 wise men and 6 judges. They are in charge of trials for crimes committed by shinigami in any realm, and can command the Gotei 13's use of military force.

The military branch of the Soul Society, made up of 13 different divisions that normally operate separately within their own assigned jurisdictions.
Captain-Commander: The title given to the individual in charge of the Gotei 13.
Captain: The title given to the individuals in charge of each of the 13 divisions. They operate beneath the Captain-Commander, but are not usually required to report to him unless he specifically requests it.
Lieutenant: The title given to the second seat of each division, operating beneath the Captain but above the rest of the members of their division.

The primary weapon used by shinigami, typically in the form of a blade of some kind. They are also used by Arrancar and Visored. No two zanpakutou are the same, and they each have their own individual spirit.
Sealed: A zanpakutou's standard form, generally in the shape of a sword with some variation.
Shikai: Once a shinigami learns their zanpakutou's name, they can release the weapon's upgraded form, where it takes on a different shape and its wielder has access to more of its power.
Bankai: The final upgraded form of the zanpakutou, wielded by only the most powerful shinigami. The weapon's shape alters, and the wielder can summon its spirit to the corporeal realm.

Particles, similar to but incompatible with atoms, that make up souls and spiritual matter. All shinigami and Hollows, as well as their individual realms, are made entirely of reishi.
Reiryoku: or "Spiritual Power," is an individual's internal energy based on their spiritual sensitivity and will, released by shinigami to power their abilities during combat. The larger the amount of reiryoku, the more powerful the shinigami is, if they can control it. Reiryoku is stored energy, remaining dormant.
Reiatsu: or "Spiritual Pressure," is the physical embodiment of a person's reiryoku when it is released, willingly or unwillingly. Reiatsu is energy in use, and its power is based both on its original latent potential and the individual's ability to manipulate it.

Corrupt human souls that have succumbed to despair or rage, or have remained in the world of the living for too long. They devour the souls of humans, living and dead alike, and grow stronger the more they consume.
Arrancar: Hollows that have obtained the powers of shinigami, the opposite of Visored.
Espada: The highest ranking Arrancar, of which there are ten ranked in ascending order.

A separate dimension that houses Hollows and Arrancar. There is no government, and status is based entirely upon level of power.
Las Noches: The headquarters of the army of Arrancar.

Humans with heightened spiritual awareness capable of destroying Hollows. Because their methods completely eradicate the corrupted souls of Hollows, rather than purifying them, they disrupt the balance of life and death, blurring the line between the two which would eventually destroy the world. Because of this, they were nearly eradicated by the Soul Society.
Schatten Bereich: The "shadow realm" that exists in tandem with the Seireitei, where the Wandenreich have lived for 1,000 years.
Wandenreich: A hidden group of Quincy living in the Schatten Bereich after they lot the war againt the Soul Society. They have been plotting overtake the Soul Society, and consequently it's immeasurable supply of reishi, ever since.