I was afraid of my boss (a middle manager) for ages... Was the kind that would lash out and even swear at you/threaten you (while no one else was around to witness it of course). One day at my wits end I called his bluff though I was serious at the same time (had threatened that unless I did such and such I'd be out the door) and said that in light of his warning I'd start looking for another job. Well, he calmed down super fast from his rant and backed off... Even got me a Christmas present a few weeks later. Never apologised for the months of hell... But at least he didn't do it again. Worked out well in my case but it sure was draining up to that point.