Nicholas John Simper (born 3 November 1945) is an English bass guitarist, who was a co-founding member of Deep Purple and Warhorse.

In the 1960s, he began his professional career in bands such as Johnny Kidd & the Pirates, The Flower Pot Men, and Lord Sutch's Savages.

Prior to co-founding Deep Purple in 1968, Simper played for a number of bands, including The Renegades (1960–61), The Delta Five (1961–63), Some Other Guys (1963–64), Buddy Britten & The Regents renamed Simon Raven Cult (1964–66) and Johnny Kidd & the Pirates.

When new singer Ian Gillan from the band Episode Six was sought as a replacement for Evans, bandmate Roger Glover tagged along to play bass at some rehearsals and recorded the single "Hallelujah" for Deep Purple.

After his departure, he briefly worked with Marsha Hunt before forming his own band Warhorse, that recorded two albums for Vertigo.

During this time, Simper also played on a Lord Sutch live album, along with Ritchie Blackmore and Keith Moon.

On 9 October 1976, Simper took part in the Johnny Kidd 10th Anniversary Memorial Show at the Edwardian Club at the Loughborough Hotel in Brixton.

During a gig in Austria in 2007, Simper performed the Deep Purple song "Emmaretta" with the support band Nasty Habits.

In 2010, Simper and Nasty Habits played more shows presenting "The Deep Purple Mark One Songbook" in Austria, Switzerland, Hungary and Poland while an album was in the making.