The Source
In Act 1, Scene 2, Line 51 of Hamlet, Laertes refers to King Claudius as a Dread lord:
KING CLAUDIUS We doubt it nothing: heartily farewell.
Exeunt VOLTIMAND and CORNELIUS
And now, Laertes, what's the news with you?
You told us of some suit; what is't, Laertes?
You cannot speak of reason to the Dane,
And loose your voice: what wouldst thou beg, Laertes,
That shall not be my offer, not thy asking?
The head is not more native to the heart,
The hand more instrumental to the mouth,
Than is the throne of Denmark to thy father.
What wouldst thou have, Laertes?
LAERTES My dread lord,
Your leave and favour to return to France;
From whence though willingly I came to Denmark,
To show my duty in your coronation,
Yet now, I must confess, that duty done,
My thoughts and wishes bend again toward France
And bow them to your gracious leave and pardon.
There is seemingly no special significance to this single line which has been, in the grand design of all things Shakespeare, altered inexplicably between versions of the play; the line is sometimes written as "Dread, my lord." The line may be foreshadowing certain events and information revealed later in the play, and it is definately the result of Shakespeare's certain poetic flare. Despite relative obscurity in the face of more memorable quotes and monologues it remains a strangely memorable phrase, and has likely served as the source of the title "Dread Lord" in various other contexts.
In Blizzard Entertainment's Warcraft III, the Dread Lord is a Hero of the Undead race. His skills are Carrion Swarm, Sleep, Vampiric Aura, and Inferno. In the storyline they play the roles of demonic generals under the command of either Kil'jaiden or Archimonde. It is quite likely that the source of the title "Dread Lord" is related to the line in Hamlet; The People at Blizzard are smart fellows. The Dread Lord character is relatively arrogant, and seems to be running the show, although there are larger powers at work behind the scenes. The Dread Lords are always portrayed as a bit traitorous, even though no actual treason is committed until late in The Frozen Throne Campaign. The similarities of Tichondrius, Malganis, and the other dreadlords to King Claudius is passing at best. It is also possible that Blizzard simply made it up.
The Dread Lord in Your Life
In the mundane world of men, there also exist those beings that might be described as Dread Lords. The sort of person who always seems to know what others are thinking, or what they will do before they do it. A Dread Lord is someone with a unique understanding of human nature, and a willingness to use that knowledge. Although the term "Dread Lord" is commonly associated with elemental evil, this is not necessarily the case. A certain diabolic aura is often achieved by simple willingness to manipulate others, whether the goal is harmful or constructive. Dread Lords prefer to exert their power from behind the scenes, and do not commonly make spectacles of themselves.
Dread Lords are drawn to positions involving people and ideas, because this is their own element. Although most Dread Lords can be found working as teachers, advisors, consultants, councilors, or psychologist, the converse is not necessarily true; teaching and advising professions are not primarily staffed by Dread Lords. This is not a firm rule by any means; Dread Lords are comfortable anwhere that they can blend into the crowd and work their magic. Dread Lords can be found in any walk of life, but actually finding one is a bit like finding a four-leaf clover.
There are two basics types of Dread Lord. The Dread Lord who is primarily concerned with using others to attain his own selfish goals might be called an Epimethian Dread Lord. Epimethian Dread Lords are generally amoralists, willing to use others to aid themselves, and have no aversion to hurting others if need be. These are the "bad" Dread Lords, for those who prefer to look at things in black and white. It is important to recognize who they are to prevent yourself from becoming an unwitting pawn. The Epimethian Dread Lord is the most common type, but is alo the easiest to detect.
The second type of Dread Lord is the type who manipulates people in such a way as to improve the general status of the immediate society. These are the Promethian Dread Lords. Although they are not entirely unselfish, usually occupied with proving to themselves that they are powerful, their energy is used in a more positive way. Their primary concern is to help people, although it is not necessarily in the friendliest of ways. The Promethian Dread Lord loves the Hard Lesson, and does nothing without a reason. These Dread Lords will commonly utilize negative peer pressure to influence others, but will influence them to do something which is ultimately productive for them and others. Promethian Dread Lords are not particularly concerned with their popularity. They will sometimes enjoy being hated for providing a service. It is possible that a feeling of martyrdom that they get from this helps to drive them on their unending crusade.