Shylok-a Villan or Victim

I wouldn't call him a hero. He's definitely a villain in the piece: malicious and with murder and vengeance in his heart.

What makes him interesting as a character, though, is that he's a villain with a back story. He's not simply evil, which makes a villain rather trivial and boring. Instead, you know exactly what his grievance is, and it's a very valid choice in performance to highlight his humanity.

Shakespeare did very well by some of his villains. Richard III and Macbeth are the stars of their plays. They are also murderous, but they get to talk to the audience and explain their motivations. Iago is a bit more opaque, but there's plenty of good text there to make him a full, rich human being, even without being able to see through his conflicting back-stories to the truth of him. The conflicting stories are themselves a strong basis for character choices.

These are villains, definitely not heroes, or even anti-heroes. But it gives Antonio the chance to be an anti-hero. He, not Shylock, is the Merchant of Venice, and Shylock's very real grievances color our perception of his character. He is not admirable, even if he doesn't deserve the death that Shylock has planned for him.

Shakespeare loved his anti-heroes as much as he loved his villains. They all have tragic flaws: the impetuosity and ego of Romeo and Juliet; the jealousy and gullibility of Othello; the stiff-necked pride of Coriolanus. Shakespeare wanted us to identify with both his heroes and his villains because their flaws are our flaws, and the distinction between anti-hero and villain can be kind of blurry.

I wouldn't put Shylock in the category of anti-hero: he is more sinning than sinned against. But he is still human, and that's more important than the assignment of him to a category.