Minecraft: All About Minecraft

Lets start with Mobs:

   "Mob" actually derives from the term mobile, and they naturally occur in the OVER-WORLD, NETHER, and END. There are Utility mobs, Passive mobs, Hostile mobs, and Neutral mobs.
  •    Utility: Snow Golem.
  •    Passive: Cow, Pig, Chicken, Sheep, Mooshroom, Squid, Villager.
  •    Hostile: Creeper, Blaze, Ghast, Magma Cube, Slime (Large), Zombie, Skeleton, Cave Spider, Spider, Silverfish, Spider Jockey.
  •    Neutral: Enderman, Wolf, Zombie Pigman.
   There is one boss per world, and he t=can be found in the END. He is the Enderdragon.