Gentle Giant formed out of the blues based (and later psychedelic) group Simon Dupree & The Big Sound in 1970, which featured the multi-instrumental Shulman brothers Derek Shulman, Ray Shulman, and Phil Shulman. They joined with guitarist Gary Green, keyboard player Kerry Minnear, and a series of drummers (John Weathers most consistently, also Martin Smith and Malcom Mortimore) to play music beyond the scope of ordinary rock, though with still a hint of blues in Green's guitar. Minnear's elaborate arrangements featured elements of both medieval polyphony and twentieth century composition.

In particular, the complex four-part vocal arrangements give the band its unusual character, with each part functioning independently rather than forming simple harmonies. The instrumental parts were just as complex, often featuring interlocking parts often in odd meters, all backed by a solid drum pattern. Cello, violin, recorder, saxophone, and vibraphone (all handled by band members) figure prominently in the arrangements in addition to Minnear's keyboards.

The band took their name in tribute to the giant Pantagruel from the satirical Renaissance fiction of Rabelais. The band disbanded in 1980.