One of my co-workers bullies me. He's making my life miserable, and it's affecting my work. How can I make him stop?

Standing up to bullies yourself is counterproductive because they thrive on confrontations with someone they believe they have power over. Making the problem worse is the fact that company management usually doesn't act to stop workplace bullies unless it's forced to do so. That means you'll have to take the initiative with management, not the bully.

First, call out the behavior to the most senior manager in your organization that you believe has the power and the will to see that this is stopped. You must be specific in describing the behavior (document as much as possible) and its debilitating effect on you. Additionally, request not only that the person's behavior be dealt with, but also that the company establishes a zero-tolerance policy against such workplace abuse. Be clear that it is reasonable to request that employees be able to carry out their work-related duties in a bully-free environment. Let management deal with your tormenter, and watch for the creation of policies that offer consequences for such misconduct. By approaching the problem this way, you'll be fighting back in the most effective way possible.