Adam Keefe Horovitz, popularly known as Ad-Rock, is an American rapper, guitarist, and actor. He was a member of the hip-hop group Beastie Boys. While Beastie Boys were active, Horovitz performed with a side project, BS 2000. After the group disbanded in 2012 following the death of member Adam Yauch, Horovitz has participated in a number of Beastie Boys-related projects, worked as a remixer, producer, and guest musician for other artists, and has acted in a number of films.

Beastie Boys were an American hip hop/rap rock group from New York City, formed in 1981. The group was composed of Adam "Ad-Rock" Horovitz, Adam "MCA" Yauch, and Michael "Mike D" Diamond. Beastie Boys were formed out of members of experimental hardcore punk band The Young Aborigines, which was formed in 1979, with Diamond on drums, Jeremy Shatan on bass guitar, John Berry on guitar, and Kate Schellenbach later joining on percussion. When Shatan left New York City in the summer of 1981, Yauch replaced him on bass and the resulting band was named Beastie Boys. Berry left shortly thereafter and was replaced by Horovitz.