Run-D.M.C.

More than any other hip-hop group, Run-D.M.C. are responsible for the sound and style of the music. As the first hardcore rap outfit, the trio set the sound and style for the next decade of rap. With their spare beats and excursions into heavy metal samples, the trio were tougher and more menacing than their predecessors Grandmaster Flash and Whodini. In the process, they opened the door for both the politicized rap of Public Enemy and Boogie Down Productions, as well as the hedonistic gangsta fantasies of N.W.A. At the same time, Run-D.M.C. helped move rap from a singles-oriented genre to an album-oriented one -- they were the first hip-hop artist to construct full-fledged albums, not just collections with two singles and a bunch of filler. By the end of the '80s, Run-D.M.C. had been overtaken by the groups they had spawned, but they continued to perform to a dedicated following well into the '90s.