In the 3rd edition game mechanics, all creatures (Player Characters and Non-Player Characters) were broken up into one of sixteen creature types. Anything not falling into one of these creature types was considered an object. The initial 15 creature types were listed in the Monster Manual, with the 16th creature type, deathless, introduced in the Eberron Campaign Setting. Each creature type has its own definitions for character creation. In addition to creature types, many creatures also had subtypes; these additional subtypes might specify a race (angel, archon, baatezu, dragonblood, dwarf, eladrin, elf, goblinoid, guardinal, halfling, reptilian, tanar'ri), an alignment (chaotic, evil, good, lawful), an element (air, cold, earth, fire, water), an environment (aquatic, extraplanar, native), a trait (incorporeal, shapechanger, swarm), or when an event changes a type (augmented).
4th edition has abandoned this structure, in favor of a less rigid structure of traits, though some of the terms remain the same.
Below are the 16 creature types. Within each category are the various races or creatures of each type listed.