The Ringling Bros. and Barnum & Bailey Circus, also known as the Ringling Bros. Circus, Ringling Bros.,the Barnum & Bailey Circus, Barnum & Bailey or simply Ringling was an American traveling circus company billed as The Greatest Show on Earth. It and its predecessor shows ran from 1871 to 2017. Known as Ringling Bros. and Barnum & Bailey, the circus started in 1919 when the Barnum & Bailey's Greatest Show on Earth, a circus created by P. T. Barnum and James Anthony Bailey, was merged with the Ringling Bros. World's Greatest Shows. The Ringling brothers had purchased Barnum & Bailey Ltd. following Bailey's death in 1906, but ran the circuses separately until they were merged in 1919.

After 1957, the circus no longer exhibited under its own portable "big top" tents, instead using permanent venues such as sports stadiums and arenas. In 1967, Irvin Feld and his brother Israel, along with Houston Judge Roy Hofheinz, bought the circus from the Ringling family. In 1971, the Felds and Hofheinz sold the circus to Mattel, buying it back from the toy company in 1981. Since the death of Irvin Feld in 1984, the circus had been a part of Feld Entertainment, an international entertainment firm headed by his son Kenneth Feld, with its headquarters in Ellenton, Florida.

With weakening attendance, many animal rights protests, and high operating costs, the circus performed its final show on May 21, 2017, at Nassau Veterans Memorial Coliseum and closed after 146 years.