Joseph Robert Saddler (born January 1, 1958), known by his stage name Grandmaster Flash, is an American musician and DJ. He created a DJ technique called the Quick Mix Theory. This technique serviced the break-dancer and the rapper by elongating the drum breaks through the use of duplicate copies of vinyl. This technique gave birth to cutting and scratching. It also gave rappers better music with a seamless elongated bed of beats to speak on. He also invented the slipmat.

He is the founder and creator of Grandmaster Flash and the Furious Five, the first rap group to be inducted into the Rock and Roll Hall of Fame in 2007. In 2019 he became the first hip hop artist to be honoured with the Polar Music Prize. On May 21, 2022, he acquired an honorary doctorate in Fine Arts from Buffalo State University. On June 1, 2023, he was awarded an honorary doctorate in music from Lehman College in the Bronx, NY. On August 4, Grandmaster was issued a proclamation from the city of New York stating that August 4th is Grandmaster Flash Day.