"Nightmare" is an instrumental composition written, produced, and performed by Italian dance musician Brainbug, released as his debut single.

The track was first issued as a single on 25 November 1996 and was re-released in the United Kingdom on 21 April 1997.

In November 1997, the song was re-issued as a double A-side with Brainbug's next single, "Benedictus", this time reaching number 24 on the UK Singles Chart and number 25 on the Irish Singles Chart.

[1] In Australia, it was ranked at number 85 on the Triple J Hottest 100 of 1997.

[3] Richard D of music website 909 Originals wrote that "Nightmare" was one of the most "sinister" dance tracks to become a chart hit while British columnist James Masterton wrote that the instrumental "owes more to the Sisters of Mercy than anything else", calling it a "chilling combination of strings and techo beats.