Hiroshi Yamauchi (Japanese: 山内 溥; 7 November 1927 – 19 September 2013) was the third president of Nintendo, serving in the role from 25 April 1949 to 24 May 2002, and principal owner of the Seattle Mariners from 1992 until his death. Before joining Nintendo, he had strong familial connections; his great-grandfather, Fusajiro Yamauchi, founded the company, and was its first president, and his grandfather, Sekiryo Kaneda, was its second president. During his tenure, Nintendo was transformed from a Japanese manufacturer of hanafuda into a global conglomerate largely focused on manufacturing video game consoles and publishing video games. On the basis of this success, and his ownership of most of Nintendo's shares, he became considerably wealthy. In 2008, he was Japan's wealthiest person, with an estimated net worth of $7.8 billion. Even in 2013, with this figure having declined to $2.1 billion, he was the 13th richest person in Japan and the 491st richest in the world.

Yamauchi was born in Kyoto to Shikanojo Inaba and Kimi (née Yamauchi}. When he was five, his father abandoned his family; his mother, unable to cope, gave up custody to her parents, including Sekiryo Kaneda, president of Nintendo. He was sent to a preparatory school in Kyoto at age twelve, and worked in a military factory during World War II, his plans to study law or engineering disrupted. After the end of the war, he studied law at Waseda University, and married Michiko Inaba. With the absence of Yamauchi's father, his grandparents met to arrange the marriage.^{[unreliable source?]}

In 1948, while Yamauchi was at Waseda University, Kaneda suffered a stroke. As he lacked a designated successor as president of Nintendo, Yamauchi was asked to replace him immediately. Yamauchi agreed on the condition that he be the only family member at Nintendo; subsequently, his older cousin was fired. Due to his age and lack of management experience, Yamauchi was resented by most employees, and not taken seriously. This perception was challenged when he responded to a factory strike by firing long-time employees who questioned his authority. Yamauchi led Nintendo, which he renamed Nintendo Karuta and moved elsewhere in Kyoto, in what was called a "notoriously imperialistic style" by video game journalist Steven L. Kent. He was the sole judge of potential new products, and he only approved those which appealed to him and his instincts.

Yamauchi introduced Western (plastic-backed) playing cards to Japan, achieving success in 1959, with the release of a pack of officially licensed cards featuring Disney characters, accompanied by a booklet explaining different card games. That their association with gambling, technically illegal in Japan, had limited the popularity of Western-style cards did not stop the sale of 600,000 packs within a year, helping Nintendo to dominate the Japanese playing card market.

Yamauchi took Nintendo, renamed Nintendo Company Limited, public, becoming the first chairman of the board. Convinced by a visit to the small headquarters of the United States Playing Card Company, the world's biggest manufacturer of playing cards, that Nintendo would struggle to grow if it remained on this path, he took steps to diversify the company. Nintendo's ventures, including an instant rice product, and ownership of a taxi company called Daiya, failed, bringing the company to the brink of bankruptcy. Fortunes changed in 1966, with the release of the Ultra Hand, a toy based on an extendable claw which Gunpei Yokoi, a factory engineer, was seen by Yamauchi to be playing with during a break. Relying on Nintendo's pre-existing distribution networks, Yamauchi decided to move into the toy industry. Yokoi was transferred to a new department called Games and Setup, and tasked with developing more toys. Among the products which established Nintendo as a toymaker were the Love Tester, an electronic toy which allegedly determined the strength of romantic relationships, and a light gun using solar cells for targets.

Many of Nintendo's toys included electronic components. Noticing the combination of technological developments and decreasing prices, and the rise of arcade games and video game consoles like the Magnavox Odyssey, Yamauchi realized that electronics could become foundational to Nintendo's products, as opposed to a novelty. Nintendo became the Japanese distributor of the Odyssey, and established Nintendo Research & Development Department, a unit dedicated to the development of video games. By the end of the 1970s, a second unit had been established, with employees hired from Sharp Electronics to develop the Color TV-Game 6, Nintendo's first console. The separation, deemed unique by researcher Steven Boyer, lead to competition, and, in turn, innovation. Games like Radar Scope, Space Fever, and Sheriff began appearing in arcades, though they achieved little popularity in America until 1981, when Donkey Kong, a passion project of Shigeru Miyamoto, was released.

In 1980, Nintendo introduced the Game & Watch, a series of portable video games designed by Yokoi, and featuring, newly for the time, an LCD and microprocessor. Though the product line was a hit, it was believed by Yamauchi that it lacked the depth to be a long-term success. Efforts to develop a product which could be one led to the release in 1983 of the Family Computer, a console commonly abbreviated as the Famicom. First-party titles were developed by Nintendo's R&D units; a third and fourth were established in 1980 and 1983, respectively. In the wake of the video game crash of 1983, which he believed was caused by a glut of poor-quality games, Yamauchi was not only strict about approving the release of games, but restricted third-party publishers to releasing just three titles a year. Still, games were made easy to develop, as he believed that artists, not technicians, create excellent games.

Yamauchi's confidence in the Famicom paid off. He promised an electronics company that one million units would be ordered within two years, a goal easily reached. Released outside Japan as the Nintendo Entertainment System, and redesigned to minimize its association with video games, the console was an equal smash; by 1990, the majority of consoles historically sold were NESes or Famicoms.