There is a stencil and graffiti tradition of memorializing people who have been senselessly killed, usually for unjust reasons. Jairo Mora Sandoval, a Costa Rican environmentalist, his likeness is pictured in the above photo, is now becoming an icon for those who hold the flora and fauna of the planet dear. Go here to read more about Sandoval's assassination.
Here are some other people, senselessly killed, who have lived on as stencil icons:
Oscar Grant, killed by BART police in Oakland, CA (while face down on the ground)
Brad Will, killed by police in Oaxaca, MX (while filming a protest)
Nour Zahra, killed while protesting the dictatorship in Syria