Sir Clive Marles Sinclair was an English entrepreneur and inventor, most commonly known for his work in consumer electronics in the late 1970s and early 1980s. 

Inventor of the pocket calculator, ZX80, ZX81, ZX Spectrum

After spending several years as assistant editor of Instrument Practice, Sinclair founded Sinclair Radionics in 1961, where he produced the first slim-line electronic pocket calculator in 1972 (the Sinclair Executive). Sinclair later moved into the production of home computers and produced the Sinclair ZX80, the UK's first mass-market home computer for less than £100, and later, with Sinclair Research, the ZX81 and ZX Spectrum; the latter is widely recognised by consumers and programmers for its importance in the early days of the British and wider European home computer industry. 

In Eastern Europe homemade ZX Spectrum clones were the only affordable computing equipment for a long period till the mid 1990s.

Sinclair Research also produced the TV80, a flatscreen portable mini television utilising a cathode ray tube; however, LCD television technology was in advanced development and the Sinclair FTV1 (TV80) was a commercial flop, only 15,000 units being produced.

Knighted in 1983, Sinclair formed Sinclair Vehicles and released the Sinclair C5, a battery electric vehicle that was also a commercial failure. Sinclair then concentrated on personal transport, including the A-bike, a folding bicycle for commuters that weighs 5.7 kilograms (13 lb) and folds down small enough to be carried on public transport.

Sinclair Research Ltd is a British consumer electronics company founded by Clive Sinclair in Cambridge. It was originally incorporated in 1973 as Westminster Mail Order Ltd, renamed Sinclair Instrument Ltd, then Science of Cambridge Ltd, then Sinclair Computers Ltd, and finally Sinclair Research Ltd. It remained dormant until 1976, when it was activated with the intention of continuing Sinclair's commercial work from his earlier company Sinclair Radionics, and adopted the name Sinclair Research in 1981.

In 1980, Clive Sinclair entered the home computer market with the ZX80 at £99.95, at that time the cheapest personal computer for sale in the United Kingdom. In 1982 the ZX Spectrum was released, becoming the UK's best selling computer, and competing aggressively against Commodore and Amstrad.