Keith Matthew Thornton, better known by his stage name Kool Keith, is an American rapper and record producer from The Bronx, New York City, known for his surreal, abstract and often profane or incomprehensible lyrics. Kool Keith has recorded prolifically both as a solo artist and in group collaborations. Kool Keith is generally considered to be one of hip-hop's most eccentric and unusual personalities.

The Ultramagnetic MCs is an American hip hop group based in the Bronx, New York City. Founded by Kool Keith, the group also includes Ced Gee, TR Love, and Moe Love. Tim Dog became an unofficial member in 1989. In 1990, DJ Jaycee was added as a road manager and backup DJ. Big.D was put down with the crew by Kool Keith in 1989. A former member, Rooney Roon, was fired following an assault arrest. Beat-boxer Rahzel was also involved with the group early in its career. The group's work was associated with unorthodox sampling, polysyllabic rhymes, and bizarre lyrical imagery.