William Frederick Rieflin was an American musician. Rieflin came to prominence in the 1990s mainly for his work as a drummer with groups such as Ministry, the Revolting Cocks, Lard, KMFDM, Pigface, Swans, Chris Connelly, and Nine Inch Nails. He worked regularly with R.E.M. following the retirement of Bill Berry in 1997. He was a member of King Crimson from 2013 until his death in 2020.

Industrial metal is the fusion of heavy metal and industrial music, typically employing repeating metal guitar riffs, sampling, synthesizer or sequencer lines, and distorted vocals. Prominent industrial metal acts include Ministry, Nine Inch Nails, KMFDM, and Godflesh.