Pathfinder RPG Bestiary 4 Pocket Edition - Rules of Play says:
What is a hero without monsters to vanquish? This 328-page book presents hundreds of different creatures for use in the Pathfinder Roleplaying Game. Within this tome you'll find fire-breathing dragons and blood-drinking vampires, vile demons and shapechanging werewolves, sadistic goblins and lumbering giants, and so much more! Yet not all the creatures in this book are enemies, for some can serve lucky heroes as allies or advisors, be they summoned angels or capricious nymphs. And it doesn't stop there—with full rules for advancing monsters, adapting monsters to different roles, and designing your own unique creations, you'll never be without a band of hideous minions again!