Abstract: The “Kydian revenge tragedy”, initiated by Thomas Kyd, had a profound impact upon Hamlet and the other early modern English tragedies. By adopting the “play within the play” mode in The Spanish Tragedy, Kyd reveals, vividly, the entire process of how a revenger degenerates gradually from an innocent victim into a Machiavellian villain. However, if we either simply define revenge as “wild justice” and the loss of rationality or place a one-sided emphasis on the ethical dilemma of revenge in early modern period, we would, to a great extent, underestimate and overlook the key role of the emotional factors in the early modern English theater. The sensational effect of The Spanish Tragedy on the early modern English stage can be ascribed to its representation of the tragic hero's grief and wrath, the two basic emotions of humankind.

Key words: Kyd, The Spanish Tragedy, grief, wrath