John Weider (born 21 April 1947) is an English rock musician who plays guitar, bass, and violin.

[3] By 1969, Weider was in California playing in a group called Stonehenge, members of whom would later form Crabby Appleton,[4] when Ric Grech abruptly left Family to join Eric Clapton, Steve Winwood and Ginger Baker in the new 'supergroup' Blind Faith during Family's first U.S. tour and the band needed a new bassist immediately.

Weider joined midway through the tour, which ended prematurely owing to lead singer Roger Chapman's visa problems, and a fight with rock promoter/venue owner Bill Graham, which made return visits to the U.S. difficult.

Weider later joined Stud, a group that featured guitarist-bassist Jim Cregan, who would become Family's final bass player in 1972.

The band also included the rhythm section of John Wilson and Richard McCracken from Taste, Rory Gallagher's pre-solo power trio.

Weider played violin and sang backing vocals on "Nightmare (Please Wake Me Up)", the closing track from the Who's John Entwistle's second solo album, Whistle Rymes (1972).