Iconoclast

Literally, an iconoclast is a person who destroys icons, that is, sacred paintings or sculpture.

The more common meaning in current usage is that an iconoclast is a person who carries out symbolic or quixotic acts of protest against authority figures. There is a connotation that the iconoclast opposes the imposition of authority itself rather than any particular policy or action.

There is also an article on historical iconoclasm.