In the campaign world Blackrock, most of the traditional monsters exist but with a slight modification. The main character races have already been discussed in some detail, this section will go more into the details of the iconic monsters. Below are some of my thoughts and links to the various sections.
Nothing defines Dungeon and Dragons more then the dragons (and secondly the dungeon). In advanced Dungeon and Dragons, i.e. 1st edition, dragons were fearsome and deadly. Dragons were the high level adversaries, not necessarily the boss, but not something easily faced. In 2nd and into 3rd (or 3.5) edition dragons gained age categories. Now you could fight baby dragons at low levels, minimizing and diluting the majesty that dragons are meant to represent. However even at low hit points, the claw, bite, bite routine is usually more deadly then its challenge rating represents. The last edition in 3rd edition was the additional sorcerer levels. Now dragons are not just vicious brutes, but have the miscellaneous and unpredictable powers of magic. Dragons are meant as raw manifestations of elemental power. Eternal wisdom backed by raw power.
I want to share the mythology of dragons in the Dragonlance campaign setting. At the beginning of time the gods, Paladin and his wife Takhisis, looked upon the world and together they created creatures in there own image, imbued with a small spark of divinity. These magnificient creatures were Dragons. Looking down at what they created, the gods were proud of their children, creatures that could carry on their will upon the world, to look over the lesser races as parents in their own right.
But Takhisis looked upon these beings and felt nothing but jealousy, for she had to share them with her husband. Secretly she went down to the world and whispered secret ambitions into their hearts. The five races, copper, brass, bronze, silver, and the most powerful iron, heard her dark will and each in turn began to leave the path of free will to become slaves of the wife and mother of the gods. As their hearts turned dark their scales began to tarnish. The copper became green, brass turned black, bronze tuned blue, and silver became white as the oxidation began to eat away at their previous metallic scales. The iron dragon, the twinkle in both parents eyes, was the most heavily influences by Takhisis thoughts, quickly it was overcome with rust, turning red. Some except the iron, resisted the lure of greed and selfishness and followed the ways of their father. Paladin looked upon his children and sorrow filled his heart. This betrayal by his wife was deep and painful and he cast her out of their home. Feeling the loss of his favorite, the iron dragons, he sought a metal that would never be tarnished, corroded by his wife's black heart. With this in mind he created the gold dragons. Their scales always bright, never to tarnish, he set his only child created on his own loose in the world, to lead those who have chosen to follow his ways.
In Dragonlance, this myth of the Dragons is what the world's foundation was created on.