The Commodore 64, also known as the C64, is an 8-bit home computer introduced in January 1982 by Commodore International (first shown at the Consumer Electronics Show, January 7–10, 1982, in Las Vegas). It has been listed in the Guinness World Records as the highest-selling single computer model of all time, with independent estimates placing the number sold between 12.5 and 17 million units. Volume production started in early 1982, marketing in August for US$595 (equivalent to $1,670 in 2021). Preceded by the VIC-20 and Commodore PET, the C64 took its name from its 64 kilobytes (65,536 bytes) of RAM. With support for multicolor sprites and a custom chip for waveform generation, the C64 could create superior visuals and audio compared to systems without such custom hardware.

The C64 dominated the low-end computer market (except in the UK and Japan, lasting only about six months in Japan) for most of the later years of the 1980s. For a substantial period (1983–1986), the C64 had between 30% and 40% share of the US market and two million units sold per year, outselling IBM PC compatibles, Apple computers, and the Atari 8-bit family of computers. Sam Tramiel, a later Atari president and the son of Commodore's founder, said in a 1989 interview, "When I was at Commodore we were building 400,000 C64s a month for a couple of years." In the UK market, the C64 faced competition from the BBC Micro, the ZX Spectrum, and later the Amstrad CPC 464. but the C64 was still the second most popular computer in the UK after the ZX Spectrum. The Commodore 64 failed to make any impact in Japan. The Japanese market was dominated by Japanese computers, such as the NEC PC-8801, Sharp X1, Fujitsu FM-7, and MSX.

Part of the Commodore 64's success was its sale in regular retail stores instead of only electronics or computer hobbyist specialty stores. Commodore produced many of its parts in-house to control costs, including custom integrated circuit chips from MOS Technology. In the United States, it has been compared to the Ford Model T automobile for its role in bringing a new technology to middle-class households via creative and affordable mass-production. Approximately 10,000 commercial software titles have been made for the Commodore 64, including development tools, office productivity applications, and video games. C64 emulators allow anyone with a modern computer, or a compatible video game console, to run these programs today. The C64 is also credited with popularizing the computer demoscene and is still used today by some computer hobbyists. In 2011, 17 years after it was taken off the market, research showed that brand recognition for the model was still at 87%.