David William Sims (born September 17, 1963 in Austin, Texas) is an American musician, best known as the bass guitarist of the bands Scratch Acid (with whom he initially played guitar), Rapeman, and The Jesus Lizard. In addition, he has recorded or performed with Sparklehorse, Rhys Chatham, Shivaree, Pigface, Flour, and others. Sims currently performs experimental solo electric bass as Unfact.