JR

For this post, I choose to JR. He is a French artist, who start in Paris doing graffitis for then pass to the photography or "photograffeur", like he describe yourself. 
This guy make huge portraits of different persons and different themes, deal with social problems, like Gaza Strip conflict. His work is completely politic and rambler, ever on the streets and with common people, paste increase photographies on street walls, roofs, stairs, etc.
The work method is talk with people of the place; He listen what they say and later think how to realise the photographies; so that his job is very accepted, turn into illegal to allow, recongnised and reward.
This photographer is my favorite for his commitment and simplicity for show his way of looking in hard topics.