Fantasci20: Creature Creator

From the introduction: Monsters in Fantasci work much like any other type of character. That is, they use the same six classes as any other character, the same skills and the same feats and so forth. The only difference between a monster and a character are in the realm of backgrounds, occupations, hobbies or Reputation. Creatures do not normally have these items, though intelligent creatures might at the game master’s discretion. This section offers some new feats as well as guidelines to allow you to build a wide array of monsters and creatures.