The Intellivision is a home video game console released by Mattel Electronics in 1979. The name is a portmanteau of "intelligent television". Development began in 1977, the same year as the launch of its main competitor, the Atari 2600. In 1984, Mattel sold its video game assets to a former Mattel Electronics executive and investors, eventually becoming INTV Corporation. Game development ran from 1978 to 1990 when the Intellivision was discontinued. From 1980 to 1983, more than 3 million consoles were sold.

The Intellivision was developed at Mattel in Hawthorne, California along with the Mattel Electronics line of handheld electronic games. Mattel's Design and Development group began investigating a home video game system in 1977.Mattel identified a new but expensive chipset from National Semiconductor and negotiated better pricing for a simpler design. Its consultant, APh Technological Consulting, suggested a General Instrument chipset, listed as the Gimini programmable set in the GI 1977 catalog. The GI chipset lacked reprogrammable graphics and Mattel worked with GI to implement changes. GI published an updated chipset in its 1978 catalog. After having chosen National in August 1977, Mattel waited for two months before ultimately choosing the proposed GI chipset in late 1977. A team at Mattel, headed by David Chandler, began engineering the hardware, including the hand controllers. In 1978, David Rolfe of APh developed the onboard executive control software named Exec, and with a group of Caltech summer student employees programmed the first games. Graphics were designed by a group of artists at Mattel led by Dave James.

The Intellivision was introduced at the 1979 Las Vegas CES in January as a modular home computer with the Master Component priced at US$165 and a soon-to-follow Keyboard Component also at $165 (equivalent to $620 in 2021). At Chicago CES in June, prices were revised to $250 for each component. A shortage of key chips from manufacturer General Instrument resulted in a limited number of Intellivision Master Components produced that year. In Fall 1979, Sylvania marketed its own branded Intellivision at $280 in its GTE stores at Philadelphia, Baltimore, and Washington, D.C. On December 3, Mattel delivered consoles to the Gottschalks department store chain headquartered in Fresno, California with a suggested list price of $275. The Intellivision was also listed in the nationally distributed JCPenney Christmas 1979 catalog along with seven cartridges. It was in stores nationwide by mid-1980 with the pack-in game Las Vegas Poker & Blackjack, and a library of ten cartridges. Mattel Electronics became a subsidiary in 1981.

Though the Intellivision is not the first system to have challenged Warner Communications's Atari, it is the first to have posed a serious threat to the market leader. A series of advertisements starring George Plimpton use side-by-side game comparisons to demonstrate the superior graphics and sound of Intellivision over the Atari 2600. One slogan calls Intellivision "the closest thing to the real thing". One example compares golf games where the other console's games have a blip sound and cruder graphics, while the Intellivision features a realistic swing sound and striking of the ball, and a more 3D look. There is an advertisement comparing to the Atari 2600, with the slogan "I didn't know". In its first year, Mattel sold out its initial 175,000 production run of Intellivision Master Components. In 1981, more than one million Intellivision consoles were sold, five times as many as in 1980.