John Lee Curtis "Sonny Boy" Williamson (March 30, 1914 – June 1, 1948) was an American blues harmonica player, singer and songwriter. He is often regarded as the pioneer of the blues harp as a solo instrument. He played on hundreds of recordings by many pre–World War II blues artists. Under his own name, he was one of the most recorded blues musicians of the 1930s and 1940s and is closely associated with Chicago producer Lester Melrose and Bluebird Records. His popular songs, original or adapted, include "Good Morning, School Girl", "Sugar Mama", "Early in the Morning", and "Stop Breaking Down".

Williamson's harmonica style was a great influence on postwar performers. Later in his career, he was a mentor to many up-and-coming blues musicians who moved to Chicago, including Muddy Waters. In an attempt to capitalize on Williamson's fame, Aleck "Rice" Miller began recording and performing as Sonny Boy Williamson in the early 1940s, and later, to distinguish the two, John Lee Williamson came to be known as Sonny Boy Williamson I or "the original Sonny Boy".