Animate Dead

(Player's Handbook v.3.5, p. 198)

Necromancy [Evil]
Level: Death Master 2, Cleric 3, Death Delver 3, Adept 3, Blighter 4, Wizard 4, Wu Jen 4, Sorcerer 4, Sha'ir 4, Dread Necromancer 4, Death 3, Undeath 3,
Components: V, S, M,
Casting Time: 1 standard action
Range: Touch
Target: One or more corpses touched
Duration: Instantaneous
Saving Throw: None
Spell Resistance: No

This spell turns the bones or bodies of dead creatures into undead skeletons or zombies that follow your spoken commands. The undead can follow you, or they can remain in an area and attack any creature (or just a specific kind of creature) entering the place. They remain animated until they are destroyed.
(A destroyed skeleton or zombie can't be animated again).

Regardless of the type of undead you create with this spell, you can't create more HD of undead than twice your caster level with a single casting of animate dead. (The deserate spell doubles this limit; see page 218).

The undead you create remain under your control indefinitely. No matter how many times you use this spell, however, you can control only 4 HD worth of undead creatures per caster level. If you exceed this number, all the newly created creatures fall under your control, and any excess undead from previous castings become uncontrolled. (You choose which creatures are released). If you are a cleric, any undead you might command by virtue of your power to command or rebuke undead do not count toward the limit.

Skeletons: A skeleton can be created only from a mostly intact corpse or skeleton. The corpse must have bones, so creating a skeleton from a purple worm, for example, is not possible. If a skeleton is made from a corpse, the flesh falls off the bones. The statistics for a skeleton depend on its size; they do not depend on what abilities the creature may have had while alive. The Monster Manual has game statistics for skeletons.

Zombies: A zombie can be created only from a mostly intact corpse. The corpse must be that of a creature with a true anatomy, so a dead gelatinous cube, for example, cannot be animated as a zombie. The statistics for a zombie depend on its size, not on what abilities the creature may have had while alive. The Monster Manual has game statistics for zombies.

Material Component: You must place a black onyx gem worth at least 25 gp per Hit Die of the undead into the mouth or eye socket of each corpse you intend to animate. The magic of the spell turns these gems into worthless, burned-out shells.