THE BULLY - someone who deliberately intimidates others.
Bullies pose a problem at work whether they're subordinates, colleagues, or bosses. A bully who works for you may steer clear of your authority but take advantage of your other team members. Your team members will look to you to protect them, so you wind up battling the Bully anyway. If the Bully is your peer, you have just as much of a problem on your hands but little or no authority to deal with it. If the Bully is your boss, you're vulnerable.