They have the ability to pick up and move blocks around. They are generally peaceful. If you look at them, by placing your crosshair directly over them, they freeze, stare back at you, and become hostile. They stay frozen as long as you keep looking at them. When you look away, they will quickly run towards you; if they are a long distance away, they will teleport several times until close enough to reach you. Endermen can teleport about once per second.