Grand Mixer DXT (born Derek Showard) is an American turntablist. He was formerly known as Grand Mixer D.ST. "D.ST" is a reference to Manhattan, New York City's Delancey Street on the Lower East Side. He was featured in the influential hip hop film Wild Style.

Widely recognized as a pioneer, Grand Mixer DXT is credited for being the first to establish the turntable as a fully performable and improvisational musical instrument (Alberts 2002). Especially important is his technique of altering the pitch of the note or sound on the LP record.