Uncle Sam

Uncle Sam is a personification of the U.S. federal government or of the United States in general.

A popular etymology traces the use of "Uncle Sam" to the War of 1812, when it ostensibly referred to the meat packer Samuel Wilson, whose business supplied troops in New York and New Jersey. Barrels of Wilson's meat stamped "U.S." were associated with his nickname, Uncle Sam, when in turn became a personification of the national government. 

Uncle Sam is sometimes used in the financial media to refer to the federal government, particularly in the context of income taxes.

Prior to the 19th century, the U.S. had been personified by the figure "Brother Jonathan," originally a derogatory term for Puritans during the English Civil War. Female representations of the U.S. are also common: Columbia and, since the 20th century, Lady Liberty. 

The most popular image of Uncle Sam is a World War I recruiting poster drawn by James Montgomery Flagg, which features a stern Uncle Sam pointing outward and the words, "I want YOU for U.S. Army."

Source: Wikimedia.