slave driver

a slave driver (someone who makes his / her employees work very hard for long hours) — безжалостный начальник, погоняла, настоящий эксплуататор; ~тиран и деспот; ~тиран и сумасброд (ирон.);

Example: My boss is such a slave driver! — У меня изверг, а не начальник.

cf
[throw one's weight about]
order sb around