Someone who deliberately gives others a hard time, is very demanding, or is insulting. Can be considered vulgar slang. John's boss, Mark, is quite the ball-breaker. After completing the project ahead of time and under budget, Mark ordered John to work through the weekend to finish up other meaningless tasks.
a ball-breaker(British & Australian very informal!)
a woman who does not like men and is unpleasant towards them I don't think you're going to like your new flat mate - she's a bit of a ball-breaker.