The Nihilist Spasm Band (NSB) is a Canadian noise band formed in 1965 in London, Ontario.

The term "spasm band" refers to a band that uses homemade instruments. Most of the NSB's instruments are modifications of other instruments, or wholly invented by the members. In addition to the homemade instruments, members are encouraged to improvise. The range of the improvisation is such that instruments are not tuned to each other, tempos and time signatures are not imposed, and the members push the ranges of their instrumentation by engaging in constant innovation and ever-increasing volume over the course of a performance.

The band was founded by Hugh McIntyre, John Clement, John Boyle, Bill Exley, Murray Favro, Archie Leitch, Art Pratten, and Greg Curnoe.

Leitch has since retired, Curnoe was struck and killed by a pickup truck while cycling in 1992. Aya Ohnishi (a Japanese fan who organized NSB tours of Japan) joined the band on drums starting in 1999. McIntyre died of heart failure in 2004.

The band members are mostly local artists from the London area.