The word iconoclastic is an adjective referring to a breaking of established rules or destruction of accepted beliefs. It might refer to an artist with an unorthodox style, or an iconoclastic attack, either physical or verbal, on a religious doctrine or image.
Consider the Greek word eikōn, or "image," coupled with -klastēs, "one who breaks," and you get a good image of someone who is iconoclastic. An iconoclastic approach to religion involves tearing down the icons representing the church. While this was once done physically, through riots and mayhem, today’s iconoclasts usually prefer using words. Not all iconoclasts are destructive, however. An iconoclastic approach to art and music has given rise to the development of new genres and styles through breaking the rules.