Jack of Blades from the first game is an ancient being who lives through the mask he wears and possesses the luckless men who wear it In the past, Jack of Blades led the burning of the kingdom of Albion for refusing to bow before him and his comrades. He burnt the home of the first game's Hero and ruthlessly blinded his sister, later killing their mother as well. Ruthless, vicious and cruel, Jack would set the standard for Fables villains to follow.
Reaver, in the second game, manages to double cross the main character at least twice and was revealed to be the person responsible for the destruction of Oakvale, though he actually regretted that action in the past (key emphasis on the past tense in that statement). In the third game he controls the Bowerstone industrial sector, which he forces children to work in factories and shoots workers who slow or grow tired, protest, or break some unannounced rule he has yet to think up. He also acts as an advisor to the king in which his suggestions will be something along the lines of deforestation and tearing down a school to make room for a whorehouse.
The monstrous Crawler of the third game is seen Mind Raping the hero's ally Walter when it first appears before attempting to do the same to the hero. It then forces Walter to relive traumatic memories and reveals it is responsible for an utter massacre in Aurora. When the Crawler attacks Albion, it can murder over six million people if the city isn't fortified enough and possesses Walter as a host. The Crawler, while an Eldritch Abomination, operates entirely by human morality and has an all too understandable personality.