Joseph Henry Nuxhall (/ˈnʌkshɔːl/; July 30, 1928 – November 15, 2007) was an American left-handed pitcher in Major League Baseball, best remembered for having been the youngest player ever to appear in a Major League game and for spending 40 years as a Cincinnati Reds broadcaster.

Nuxhall played primarily for the Cincinnati Reds. Immediately after retiring as a player, he became a radio broadcaster for the Reds from 1967 through 2004, and continued part-time up until his death in 2007. Nuxhall held the team's record for career games pitched (484) from 1965 to 1975, and still holds the team mark for left-handers. He pitched 2⁄3 of an inning for the Reds on June 10, 1944, at the age of 15 years, 316 days. Called upon for that single game due to player shortages during World War II, Nuxhall eventually found his way back to the Reds in 1952, and the National League All-Star team in 1955 and 1956. Long known as "The Ol' Left-hander," he compiled a career earned run average of 3.90 and a record of 135–117 during his 16-season career, with all but five of his victories being earned with the Reds. Nuxhall died in 2007 after a long battle with cancer.

Nuxhall was born and raised in Hamilton, Ohio. During World War II, many regular baseball players were unavailable while serving in the military. Meanwhile, Nuxhall was the biggest member of the ninth grade class in Hamilton at 6 feet 2 inches (1.88 m) and 190 pounds (86 kg)—a left-hander with a hard fastball, but not much control. Nuxhall was playing in a semi-pro league with his father for a few years. Scouts looking to fill out the Reds' depleted roster were following Orville Nuxhall, Joe's father, in 1943. But they were informed that the elder Nuxhall was not interested in signing a professional contract because of his five children. The scouts then became interested in Joe, who was only 14 at the time. After waiting until the following year's basketball season was over, Nuxhall signed a major league contract with the Reds on February 18, 1944. General manager Warren Giles intended to wait until school was over in June to add him to the team, but more of his players were inducted into the service in the spring. With permission from his high school principal, Nuxhall was in uniform with the team on Opening Day.

I was pitching against seventh-, eighth- and ninth-graders, kids 13 and 14 years old... All of a sudden, I look up and there's Stan Musial and the likes. It was a very scary situation.

On June 10, 1944, the Reds were playing the first place (and eventual World Series champions) St. Louis Cardinals at Crosley Field and were trailing 13–0 in the ninth inning when Manager Bill McKechnie called on Nuxhall for mop-up relief. He started well, retiring the first batter he faced, shortstop George Fallon, on a groundout. But he was unable to get out of the inning, yielding five walks, two hits, one wild pitch and five runs. He spent the rest of the 1944 season in the minor leagues. But unlike Jake Eisenhart, who made his debut for the Reds the same day by getting the last out of the frame but didn't return to the major league level after 1944, Nuxhall later returned to pitch in the majors eight years later in 1952.

Nuxhall remains the youngest individual to play in a major league game in history. During Nuxhall's lifetime, it was believed that a 14-year-old named Fred Chapman pitched five innings in one 1887 game. But in 2009, the Society for American Baseball Research discovered that Chapman's first name and age were both incorrect. The 1887 player was actually named Frank Chapman, and he was 25 at the time of his only major league appearance. There have also been sources listing a Billy Geer, who played for the 1874 New York Mutuals of the National Association, as being born in 1859; but this is questionable as well, as is whether the National Association was a major league.^{[citation needed]}

Joe Reliford, a 12-year-old batboy for the Class D Fitzgerald Pioneers, became the youngest person ever to play in a professional baseball game in 1952, when he was called on to pinch-hit.

Following his appearance with the Reds, he was assigned to the Birmingham Barons in the Southern League, but pitched only a third of an inning there (he struck out his first batter, then allowed a hit, five walks, a hit batter and five runs). Nuxhall attended spring training with the Reds in 1945. After school ended that spring, he pitched in the Reds minor league system for one season. Nuxhall then decided to return home until he finished high school the following year. He regained his amateur status and played football, basketball and baseball for Hamilton High School as a senior in 1945–‘46, earning all-state honors in football and basketball. Over the next five years, he played in the minor leagues with the Syracuse Chiefs, Lima Reds, Muncie Reds, Columbia Reds, Charleston Senators and Tulsa Oilers before returning to the Cincinnati Reds in 1952. He briefly returned to the minors in 1962 with the San Diego Padres.