freebooter

An adventurer who pillages, plunders, or thieves privately or for compensation; or wages ad-hoc war on other nations, similar to mercenary; also a "freeboot".

The military aspect should, however, be carefully studied, as the result may be to dispel the time-honoured connection between forest and freebooter under modern conditions with long-range rifles.

One who rehosts online media without authorization, a form of intellectual property theft; one who freeboots.