Louis "Satchmo" Armtrong (1901 - 1971)

Bro. Louis Armstrong
By 1938 Bro. Louis Armstrong was already a nationally famous jazz cornet and trumpet player, singer, and band leader. Having brought New Orleans-style jazz to an unprecedentedly wide audience, he had almost single-handedly transformed the music from a group form into an art for the individual soloist.

On May 13 of that year, in a studio session in New York, Bro. Louis Armstrong and his ten-piece orchestra recorded a jazz arrangement of the religious song, "When the Saints Go Marching In." Enormously popular, the tune became a jazz standard, as well as one of Bro. Armstrong's signature songs. The recording captured the exuberance and technical virtuosity of Bro. Armstrong's unique trumpet style.

Redhot Jazz (2nd link below) says

Louis Armstrong was the greatest of all Jazz musicians. Armstrong defined what it was to play Jazz.

Wikipedia says of him:

Armstrong was a charismatic, innovative performer whose inspired, improvised soloing was the main influence for a fundamental change in jazz, shifting its focus from collective melodic playing, often arranged in one way or another, to the solo player and improvised soloing. One of the most famous jazz musicians of the 20th century, he was first known as a cornet player, then as a trumpet player, and toward the end of his career he was best known as a vocalist and became one of the most influential jazz singers.

Read more about him here, here and here.