In the popular imagination, the term "Machiavellian" has come to be associated with behavior that is devious, amoral, and displays low cunning. The term derives from the Renaissance political thinker Niccolo Machiavelli, who in his famous treatise The Prince recommended a hard-headed, ruthlessly unprincipled approach to the obtaining and maintaining of political power.

In the Elizabethan period, when The Spanish Tragedy was written, Machiavelli's name became a byword for all that was evil and crooked in the conduct of political affairs. And in the play itself, Lorenzo is the archetypal Machiavellian villain, an unprincipled, smooth-talking intriguer who shamelessly manipulates others into getting what he wants.

Though Lorenzo was responsible for capturing Balthazar with Horatio, he sees an opportunity to marry off his sister Bel-imperia to the Portuguese prince. To that end, Lorenzo forms a cynical alliance with Balthazar, the King of Spain's great enemy, and orders his henchmen to murder Horatio, the man who's supposed to be on his side.

In his devious machinations, Lorenzo proves himself to be a traitor to the king, a man who will stop at nothing to advance his own interests, even if it means entering into an alliance with an enemy prince. This is Machiavellian behavior at its finest (or worst, depending on how you look at it).