(Aug. 04, 1901 - July 06, 1971) Louis Armstrong was an American jazz musician. Armstrong was a charismatic, innovative performer whose musical skills and bright personality transformed jazz from a rough regional dance music into a popular art form. Probably the most famous jazz musician of the 20th century, he first achieved fame as a trumpeter, but towards the end of his career he was best known as a vocalist and was one of the most influential jazz singers. He worked with Ella Fitzgerald, Duke Ellington, Bing Crosby and Sidney Bechet.