Mark Wastell (born Orsett, 1968) is an English free improvisation musician who plays cello, double bass, electronics, tam tam and percussion. He performs solo and in various group and collaborative situations, notably IST (with Simon H. Fell and Rhodri Davies) and The Sealed Knot (with Burkhard Beins and Rhodri Davies).

During the 1990s Wastell was an originator of the New London Silence, a form of free improvisation that focused on soft sounds, delicate attack and low volume. Since 1996 he has run the Confront Recordings label. Confront Recordings has been described as "one of the most original and intelligent labels of contemporary avant and improvised music". Between 2001 and 2010 he ran Sound 323, a record shop and mail order service that also hosted performances from artists including Keith Rowe, Derek Bailey, David Toop and Taku Sugimoto. During its time in operation, Sound 323 was described by Clive Bell in The Wire as "an epicentre of much of London's improvised music".