WO or Wo may refer to:
World War II (often abbreviated to WWII or WW2), also known as the Second World War, was a global war that lasted from 1939 to 1945, although related conflicts began earlier.
World War I (often abbreviated to WWI or WW1), also known as the First World War, the Great War, or the War to End All Wars, was a global war originating in Europe that lasted from 28 July 1914 to 11 November 1918. More than 70 million military personnel, including 60 million Europeans, were mobilised in one of the largest wars in history.
World War III (WWIII or WW3) and the Third World War are names given to a hypothetical third worldwide large-scale military conflict subsequent to World War I and World War II.
In demographics, the world population is the total number of humans currently living, and was estimated to have reached 7.6 billion as of March 2018.
Heywood Allen (born Allan Stewart Konigsberg; December 1, 1935) is an American director, writer, actor, comedian, and musician whose career spans more than six decades.