When defining a Machiavellian Hero, one must remember that the word hero in this context means protagonist (main character); otherwise, the combination of Machiavellian and hero becomes an oxymoron. That being said, the term applies to a protagonist who seeks political or social gain at any cost. Below are several examples.
Shakespeare's Richard III--briefly put, he orders the murders of family members in order to obtain the crown.
Milton's Satan in Paradise Lost--as Milton portrays him, the beautiful angel Satan is willing to risk all, over and over again, in order to grasp ultimate power and revenge.
Khaled Hosseini's Amir in The Kite Runner--this is a more modern version of a Machiavellian hero, but in the first section of the novel, Amir cowardly betrays his friend and then frames him so that his father can focus solely on him. Amir does change as the novel progresses and loses his selfish tendencies, but his willingness to sacrifice anything or anyone to obtain his father's approval is shocking and results in long-term repercussions for him and others.
Napoleon from Orwell's Animal Farm or the "real" Josef Stalin--both use others (such as Snowball or Trotsky) until their use is expended and then annihilate them.