It is a fact as immutable as the Third Law of Sod that there is no such thing as a good Grand Vizier. A predilection to cackle and plot is apparently part of the job spec.
After a while a tall, saturnine figure appeared from behind the pavilion. He had the look of someone who could think his way through a corkscrew without bending, and a certain something about the eyes which would have made the average rabid rodent tiptoe away, discouraged.
That man, you would have said, has got Grand Vizier written all over him. No-one can tell him anything about defrauding widows and imprisoning impressionable young men in alleged jewel caves. When it comes to dirty work he probably wrote the book or, more probably, stole it from someone else.
He wore a turban with a pointy hat sticking out of it. He had a long thin moustache, of course.
Thief: I was on to your scam all along.
Chancellor Usurper: Impossible! I spent my entire life gaining this position and the trust of the royal family in preparation for this ultimate act of betrayal!
Thief: Well, yeah. That was my first clue. You're a Chancellor. They're always backstabbers scheming to take the throne away from those who rightfully deserve it through accident of birth.
After yet another hundred years Eblis, whose doom is assured, came to worship Adam as was his custom and said: "O my Lord and my Advancer and my Preceptor in Good and Evil, whom hast thou ever beheld in all thy world, wiser and more excellent than thyself?" Adam said: "I have never seen such an one." Eblis asked: "Hast thou ever conceived of such an one?" Adam answered: "Except in dreams I have never conceived of such an one." Eblis then answered: "Disregard dreams. They proceed from superfluity of meat. Stretch out thy hand upon the world which thou hast made and take possession." So Adam took possession of the mountains which he had levelled and of the rivers which he had diverted and of the upper and lower Fires which he had made to speak and to work for him, and he named them as possessions for himself and his children for ever. After this, Eblis asked: "O, my Upholder and Crown of my Belief, who has given thee these profitable things?" Adam said: "By my Hand and my Head, I alone have given myself these things." Eblis said: "Praise we the Giver!" So, then, Adam praised himself in a loud voice, and built an Altar and a Mirror behind the Altar; and he ceased not to adore himself in the Mirror, and to extol himself daily before the Altar, by the name and under the attributes of the Almighty.
— The Enemies to Each Other, from Debits and Credits by Rudyard Kipling
Mordeth was a counselor, Mordeth was a guy who whispered poison in the ear of the king, and had a great deal of power because of it.
— Robert Jordan sums up this trope succinctly while describing one of his villains from The Wheel of Time.
It was Lazarus — of that I am certain. He alone had the king's ear and whispered dark and evil magics into it, instilling the notion of an imminent attack by Westmarch. Afraid to speak against the archbishop, the councilors nodded their empty heads in agreement and sent us off to die.
— Lachdanan's Scroll, Part 2, Diablo III