1991 in jazz:

John Birks "Dizzy" Gillespie ( /ɡɨˈlɛspi/; October 21, 1917 – January 6, 1993) was an American jazz trumpeter, bandleader, composer and, occasionally, singer.

Allmusic's Scott Yanow wrote, "Dizzy Gillespie's contributions to jazz were huge. One of the greatest jazz trumpeters of all time (some would say the best), Gillespie was such a complex player that his contemporaries ended up copying Miles Davis and Fats Navarro instead, and it was not until Jon Faddis's emergence in the 1970s that Dizzy's style was successfully recreated . . . Arguably Gillespie is remembered, by both critics and fans alike, as one of the greatest jazz trumpeters of all time."

Gillespie was a trumpet virtuoso and improviser, building on the virtuoso style of Roy Eldridge but adding layers of harmonic complexity previously unknown in jazz. His beret and horn-rimmed spectacles, his scat singing, his bent horn, pouched cheeks and his light-hearted personality were essential in popularizing bebop.

In the 1940s Gillespie, together with Charlie Parker, became a major figure in the development of bebop and modern jazz. He taught and influenced many other musicians, including trumpeters Miles Davis, Fats Navarro, Clifford Brown, Arturo Sandoval, Lee Morgan, Jon Faddis and Chuck Mangione.

Frank Vincent Zappa (December 21, 1940 – December 4, 1993) was an American composer, singer-songwriter, electric guitarist, recording engineer, record producer and film director. In a career spanning more than 30 years, Zappa wrote rock, jazz, orchestral and musique concrète works. He also directed feature-length films and music videos, and designed album covers. Zappa produced almost all of the more than 60 albums he released with the band The Mothers of Invention and as a solo artist. While in his teens, he acquired a taste for percussion-based avant-garde composers such as Edgard Varèse and 1950s rhythm and blues music. He began writing classical music in high school, while at the same time playing drums in rhythm and blues bands; he later switched to electric guitar.

He was a self-taught composer and performer, and his diverse musical influences led him to create music that was often impossible to categorize. His 1966 debut album with The Mothers of Invention, Freak Out!, combined songs in conventional rock and roll format with collective improvisations and studio-generated sound collages. His later albums shared this eclectic and experimental approach, irrespective of whether the fundamental format was one of rock, jazz or classical. His lyrics—often humorously—reflected his iconoclastic view of established social and political processes, structures and movements. He was a strident critic of mainstream education and organized religion, and a forthright and passionate advocate for freedom of speech, self-education, political participation and the abolition of censorship.