Its list of winners includes Martin Luther King, Jr., Elihu Root, Theodore Roosevelt, Woodrow Wilson, Henri La Fontaine, Mikhail Gorbachev, Aung San Suu Kyi, Nelson Mandela, Kofi Annan, Jimmy Carter, Wangari Maathai, Barack Obama, Liu Xiaobo, Juan Manuel Santos and Abiy Ahmed. There is often a lot of controversy about the award of the prize. The 2013 winner is the Organisation for the Prohibition of Chemical Weapons, making it the second year in-a-row that an organization has won the prize, after the European Union did so in 2012.