Acorn Computers Ltd. was a British computer company established in Cambridge, England, in 1978. The company produced a number of computers which were especially popular in the UK. These included the Acorn Electron, the BBC Micro, and the Acorn Archimedes. Acorn's BBC Micro computer dominated the UK educational computer market during the 1980s and early 1990s.

Though the company was broken up into several independent operations in 1998, its legacy includes the development of RISC personal computers. Its RISC OS operating system continues to be developed (as two forks) by RISCOS Ltd and RISC OS Open. Some of Acorn's former subsidiaries live on today—notably ARM Holdings, which is globally dominant in the mobile phone and PDA microprocessor market.

Due to its innovative concepts and the future success of many of its former employees,^{[citation needed]} Acorn is sometimes referred to as the "British Apple". In 2010 the company was listed by David Meyer in ZDNet as number nine in a feature of top ten fallen "Dead IT giants". Many of Britain's IT professionals gained their early experiences on Acorns, which were often more technically advanced than commercially successful US hardware.