Ai Weiwei

Ai Weiwei, in my opinion, is one of the most important living artists. Not only is his work thoughtful and original, but he is also a prominent advocate for human rights, which is not necessarily an easy thing to be in China.  He has been detained by the government at times, but is still outspoken with his beliefs.
Above are some photos of his Sunflower Seeds installation from 2010.
(that link sends you to a mini-documentary on the work)