2013 is the centenary of Wallace Coulter's birth. He was an engineer, inventor, entrepreneur and visionary. He transformed the practice of laboratory hematology with his invention of the Coulter Principle and its application to blood cell analysis, together with the company he founded to bring it and his subsequent inventions and innovations to the world. He was born in modest circumstances and he remained modest in his outlook on life, despite his magnificent achievements, his successes, his numerous prestigious awards and his wealth later in life. This article traces his early life, his career, his achievements and the immense benefits he brought to the people of this planet.