Lawful Evil
From Dragons Exodus
Lawful evil is the methodical, intentional, and frequently successful devotion to a cruel organized system.
Lawful evil characters methodically take what they want within the limits of their personal code of conduct (which are frequently their laws, as this alignment tends to only work for people in positions of power) without regard for whom it hurts. They care about tradition, loyalty, and order but not about freedom, dignity, or life. They play by the rules, but do so without mercy or compassion. They are comfortable in a hierarchy and would like to rule, but are willing to serve. They loath to break promises, and are therefore very cautious about giving their word unless a bargain is clearly in their favour.
This reluctance comes partly from their nature and partly because they depend on order to protect themselves from those who oppose them on moral grounds. Some lawful evil villains have particular taboos, such as not killing in cold blood (but having underlings do it) or not letting children come to harm (if it can be helped). They feel these personal morals put them above unprincipled villains but also know that they are protected by the orderly, systematic structure they exist in.
Anyone in a cult practising human sacrifice and torture, but with a strict code of conduct and hierarchy, a ruthless dictator, and a scheming Grand Vizier are all examples of Lawful Evil characters. Devils are considered the embodiment of Lawful Evil. A king who rules with an iron fist and kills those who oppose his rule is lawful evil. Another example is a leader of an organized crime family who demands loyalty and order and yet kills those who get in the way of business is lawful evil.