James Jeffrey "Jeff" Plewman (March 26, 1948 – May 10, 2014), better known by his stage name Nash the Slash, was a Canadian musician. A multi-instrumentalist, he was known primarily for playing the electric violin and mandolin, as well as the harmonica, keyboards, glockenspiel, and other instruments (sometimes described as "devices" on album notes).

Nash worked as a solo artist beginning in 1975; founding the progressive rock band FM in 1976. Soon after releasing the band's first album, Black Noise, in 1977, he left the band; he resumed his solo career in 1978 (it was not until after Nash's departure that the album was widely promoted, eventually charting and receiving a gold record award). He rejoined FM from 1983 to 1988, followed by a brief reunion from 1994 to 1996, all concurrent with his solo work.

Nash's music covers an eclectic range, varying from instrumental—mood-setting music, to rock and pop music with vocals. In addition to giving concert performances, he composed and performed soundtrack music for silent films, presenting these works live in movie theatres to accompany screenings of the films. Another venue for his music was in performances to accompany the viewing of paintings by surrealist painter Robert Vanderhorst, an audiovisual collaboration, which took place in 1978 and again in 2004.

Nash famously never allowed guitars on any of his solo albums and singles. He turned down Pink Floyd guitarist David Gilmour's offer to lay down a guitar track on his album Children of the Night.