William James Mitchell Jr. (born July 16, 1965) is an American video game player. Throughout the 1980s and 1990s, he was recognized for numerous records on classic video games before disputes arose over their legitimacy beginning in 2018. Mitchell has also appeared in several documentaries on competitive gaming and retrogaming.

In 1982, Mitchell was featured in a photo spread in Life along with other video game champions during the height of the golden age of arcade video games. In 1999, Mitchell has said he was the first person to attain a perfect score of 3,333,360 points on the arcade game Pac-Man. A 2007 documentary, The King of Kong: A Fistful of Quarters, follows his attempts to maintain the highest score on Donkey Kong after being challenged by newcomer Steve Wiebe.

In 2018, Mitchell's high scores on Donkey Kong were contested after members of the Twin Galaxies forums found discrepancies in the videos Mitchell had provided for The King of Kong, suggesting he had used emulation software to falsify his score. Twin Galaxies and Guinness World Records, which incorporated Twin Galaxies' scores into their records, removed Mitchell's scores based on this evidence. Mitchell then launched legal action against both organizations for defamation. While Guinness restored Mitchell's scores, Twin Galaxies countersued Mitchell. Both Mitchell and Twin Galaxies settled in 2024, and Twin Galaxies posted Mitchell's scores on a newly created historical leaderboard. Mitchell remains banned from the contemporary Twin Galaxies leaderboards.^{[citation needed]}

Mitchell's family owns the Rickey's restaurants in Hollywood, Florida, and Pembroke Pines, Florida, and he sells Rickey's World Famous Hot Sauce.

Mitchell was born on July 16, 1965, in Holyoke, Massachusetts.

In grade school, Mitchell became an avid pinball player. He was initially uninterested in video games, but as they became more popular, according to Mitchell, "[e]veryone was standing around the Donkey Kong machine and I wanted that attention". He began playing video games around the age of 16. His interest was also spurred by a friendly rivalry with a classmate, the two trying to outscore each other on both Pac-Man and Donkey Kong. Mitchell became curious whether Donkey Kong had a recorded world-record high score, and reached out to Walter Day—at Twin Galaxies, at the time a single arcade in Ottumwa, Iowa—who had started tracking such records. Day told Mitchell of a record of 1.4 million points claimed by Steve Sanders. In November 1982, Life brought several notable arcade players, including Mitchell and Sanders, to Ottumwa for a photoshoot. Mitchell challenged Sanders to Donkey Kong and demonstrated that the game had an impassable "kill screen" at level 22, while beating Sanders and setting a high score of 874,300. Later, Sanders admitted that he had lied about his previous Donkey Kong scores, and Twin Galaxies gave the record to Billy Mitchell who held it for more than 18 years. Around this time, Mitchell established a friendship with Robert Childs, who had a business buying and installing arcade cabinets in places such as laundromats.

In 1983, Mitchell was attending Chaminade-Madonna College Preparatory School. That summer, Day invited Mitchell, along with several other players from the photoshoot, to participate in the "Electronic Circus", a 40-city tour where the players would demonstrate their skill at arcade games at each stop. But the idea fell through, and Mitchell and others spent the summer months camping out at Twin Galaxies and competing for high scores on the video games there, with Mitchell focusing on only a few selected titles. Later that summer, Day founded the US National Video Game Team, a slimmer version of the Electronic Circus, which aimed to stop in a major city in each US state; but the inaugural event encountered many snags. Day continued to bring Mitchell on various trips to confirm high scores reported by players, with Mitchell frequently calling out bluffs. By 1984, Day named Mitchell the Twin Galaxies' player of the year, but due to the 1983 video game crash, Twin Galaxies had to close down its storefront in March 1984, though Day still tracked scores. After submitting a record score for BurgerTime in 1985, Mitchell moved away from video games for the next ten years, spending more time at his family's restaurant, Rickey's Restaurant, and eventually taking ownership of it.

Following Pac-Man's release in 1980, players had discovered that it too had a type of kill screen: on reaching level 256, half the screen would be filled with nonsense glyphs that made it impossible to complete the level and continue. Following a 1982 claim made by eight-year-old Jeffrey R. Yee of reaching more than 6 million points, which gained national coverage after President Ronald Reagan wrote to congratulate Yee, Mitchell worked with his friend Chris Ayra in 1983 to determine the route to the highest possible score on Pac-Man of 3,333,360, which would require a perfect no-death run and collecting all possible points on the nonsense side of level 256's split-screen, requiring knowledge of where the edible dots were.