Leroy "Horsemouth" Wallace (born 22 August 1950) is a Jamaican drummer who worked for several years at Studio One, and has worked with numerous reggae artists including The Gladiators, Inner Circle, Prince Far I, Sound Dimension, Gregory Isaacs, Burning Spear, Ijahman Levi, Bruno Blum and Pierpoljak. He starred as himself in the lead role of the film Rockers. Wallace attended the Alpha Boys School in the 1960s and early 1970s, where he studied under Lennie Hibbert. Wallace also joined The Skatalites when they reformed in the mid-1970s. Wallace has been credited with inventing the 'Rockers' rhythm.
He has also recorded as a DJ on a number of tracks, for example "Herb Vendor", produced by Lee Perry, and "Universal Love", released under the pseudonym Mad Roy.