Canon EOS (Electro-Optical System) is an autofocus single-lens reflex camera (SLR) camera series produced by Canon Inc.. Introduced in 1987 with the Canon EOS 650, all EOS cameras used 35 mm film until October 1996 when the EOS IX was released using the new and short-lived APS (Advantix/IX) film. In 2000, the D30 was announced, as the first digital SLR designed and produced entirely by Canon. Since 2005, all newly announced EOS cameras have used digital image sensors rather than film. The EOS line is still in production as Canon's current digital SLR (DSLR) range, and, with the 2012 introduction of the Canon EOS M, Canon's mirrorless interchangeable-lens camera (MILC) system.

The acronym "EOS" was chosen for Eos, the Titan goddess of the dawn in Greek mythology, and is often pronounced as a word (UK /ˈiː.ɒs/ or US /ˈiː.ɑːs/), although some spell out the letters, reading it as an initialism.