Elizabethan revenge tragedy is a genre in which an evil and immoral, but extremely powerful, person commits outrageous wrongs against the protagonist, and the protagonist becomes obsessed with revenge and eventually brings the evildoer to justice, usually in a gruesome manner, and leaving a trail of dead bodies in his wake. Major examples of the genre include The Spanish Tragedy, Hamlet, The Revenger's Tragedy, Titus Andronicus, and The White Devil.
In one way, the genre can be seen as subversive, because there is usually an evil ruler. The injured protagonist is unable to obtain justice through legitimate means, and is forced to move outside the law. Thus political power and justice seem to be opposed.
On the other hand, most revenge tragedies end with some sort of reconciliation or restoration of harmony in the political order once the evil doer has been stripped of power, suggesting that evil is not concomitant to power but an aberration of the natural order. Next, these plays are written in Britain, but none of the evil rulers are portrayed as British, and thus this implicitly contrasts the benevolence of English monarchs with the evils of Italy and similar countries. Thus one can also argue that the eventual import is to channel discontent towards foreigners, especially the Papacy and foreign monarchs and reaffirm the legitimacy of the British monarchy and Protestantism.