From publisher blurb:
A New Breed of Adventurer
Whether wondrous or wicked, some monsters have a calling that reaches beyond the ordinary existence of their kind. Traveling alongside other intrepid characters, these heroic creatures carve their places in legend with sword, spell, tooth, and claw.
This supplement for the D&D game provides everything you need to play a monster as a character or to make the monsters your heroes fight even more formidable. Inside are over 50 all-new monster classes that show how creatures develop their characteristics and abilities as they gain levels. Along with new prestige classes and monster templates, Savage Species also features new feats, spells, magic items, and more.