William Smith Monroe (/mənˈroʊ/; September 13, 1911 – September 9, 1996) was an American mandolinist, singer, and songwriter, who created the bluegrass music genre. Because of this, he is often called the “Father of Bluegrass“.

The genre takes its name from his band, the Blue Grass Boys, who named their group for the bluegrass of Monroe’s home state of Kentucky. Monroe’s performing career spanned 69 years as a singer, instrumentalist, composer and bandleader. Monroe was born on his family’s farm near Rosine, Kentucky, the youngest of eight children of James Buchanan “Buck” and Malissa (Vandiver) Monroe. His mother and her brother, Pendleton “Pen” Vandiver, were both musically talented, and Monroe and his family grew up playing and singing at home. Bill was of Scottish and English heritage. Because his older brothers Birch and Charlie already played the fiddle and guitar, Bill was resigned to playing the less desirable mandolin. He recalled that his brothers insisted that he remove four of the mandolin’s eight strings so he would not play too loudly.