Johann Sebastian Bach is now generally regarded as one of the greatest composers of all time. Many of his family were talented musicians and composers as well, and most were also called Johann!
Johann Christoph (1642-1703) and Johann Michael (1648-1694) were brothers, and cousins of J.S.Bach's father, Johann Ambrosius Bach.
Johann Christian (1735-1782) was the youngest son of J.S. Bach and became known as "The English Bach" after becoming composer to the King's Theatre, London.