Louis Daniel Armstrong (August 4, 1901 – July 6, 1971), nicknamed Satchmo or Pops, was an American jazz trumpeter and singer.

Coming to prominence in the 1920s as an innovative cornet and trumpet player, Armstrong was a foundational influence on jazz, shifting the music's focus from collective improvisation to solo performers. With his distinctive gravelly voice, Armstrong was also an influential singer, demonstrating great dexterity as an improviser, bending the lyrics and melody of a song for expressive purposes. He was also greatly skilled at scat singing, or wordless vocalizing.

Renowned for his charismatic stage presence and deep, instantly recognizable voice almost as much as for his trumpet-playing, Armstrong's influence extended well beyond jazz, and by the end of his career in the '60s, he was widely regarded as a profound influence on popular music in general: critic Steve Leggett describes Armstrong as "perhaps the most important American musician of the 20th century." Flea once proclaimed that "Louis Armstrong was probably the greatest musician that ever lived...one note implies that if he wanted to he could play ten billion notes, but just one simple note is a beautiful thing."