The amazing Nicholas Brothers, Fayard (1914-2006) and Harold Nicholas (1921-2000), have been called the greatest tap dancers of their time, perhaps ever. The brothers were born in Alabama and North Carolina, respectively, but grew up in Philadelphia during the 1920's. Their parents were both talented musicians with their own band, and Fayard and Harold Nicholas as youngsters were exposed to various vaudeville acts at the Strand Theatre, including dancing. Later as teens Fayard and Harold Nicholas performed at the famous Cotton Club in Harlem in 1932.
Amazingly, the brothers never had any formal training in dance, yet were both teachers and masters in every respect. Their style of dancing was called "Flash Dancing," a combination of tap, ballet, and acrobatics. Their most famous dance sequence---'Jumpin Jive'--- in the movie "Stormy Weather," was cited by Fred Astaire as the greatest filmed dance sequence he had ever seen. This sequence is where the brothers dance their famous "leapfrogging' move. See for yourself.
Stormy Weather 1943