Elephants eat a lot of food, partially because they are big animals, but also because they have an inneficient digestive system. Only about 45% of what these animals eat is properly digested, and the rest is expelled out their rear ends. A company in Thailand has actually figured out how to make paper out of elephant dung due to its high fiber content. One elephant actually creates enough dung to make 115 pages of paper per day!
While they don't produce as much paper as elephants, other companies have been able to create paper from panda and sheep droppings as well.