Henry Louis Aaron (February 5, 1934 – January 22, 2021), nicknamed "Hammer" or "Hammerin' Hank", was an American professional baseball right fielder who played 23 seasons in Major League Baseball (MLB), from 1954 through 1976. Considered one of the greatest baseball players in history, he spent 21 seasons with the Milwaukee / Atlanta Braves in the National League (NL) and two seasons with the Milwaukee Brewers in the American League (AL). At the time of his retirement, Aaron held most of the game's key career power-hitting records. He broke the long-standing MLB record for home runs held by Babe Ruth and remained the career leader for 33 years. He hit 24 or more home runs every year from 1955 through 1973 and is one of only two players to hit 30 or more home runs in a season at least fifteen times.

Aaron holds the MLB records for the most career runs batted in (RBIs) (2,297), extra base hits (1,477), and total bases (6,856). The total base record is remarkable in context: at the time of his retirement, he had travelled over 12 miles farther on the base paths than any other player in MLB history. Aaron is also third all-time for career hits (3,771) and fifth in runs scored (2,174). He is one of only four players to have at least 17 seasons with 150 or more hits. Aaron's ability as a hitter can be illustrated by his still having over 3,000 hits even without counting any of his home runs.

Aaron was born and raised in and around Mobile, Alabama. Aaron had seven siblings, including Tommie Aaron, who played major-league baseball with him. He appeared briefly in the Negro American League and in minor league baseball before starting his major league career. By his final MLB season, Aaron was the last former Negro league baseball player on a major league roster. During his time in Major League Baseball, and especially during his run for the home run record, Aaron and his family endured extensive racist threats. His experiences fueled his activism during the civil rights movement.

Aaron played the vast majority of his MLB games in right field, though he appeared at several other infield and outfield positions. In his last two seasons, he was primarily a designated hitter. He was an NL All-Star for 20 seasons and an AL All-Star for one season, and he holds the record for the most All-Star selections (25), while sharing the record for most All-Star Games played (24) with Willie Mays and Stan Musial. He was a three-time Gold Glove winner, and in 1957, he won the NL Most Valuable Player (MVP) Award when the Milwaukee Braves won the World Series.

After his retirement, Aaron held front office roles with the Atlanta Braves, including the senior vice president. In 1988, Aaron was inducted into the Wisconsin Athletic Hall of Fame. In 1999, The Sporting News ranked Aaron fifth on its list of the "100 Greatest Baseball Players". In 1982, he was inducted into the National Baseball Hall of Fame in his first year of eligibility. That same year, MLB introduced the Hank Aaron Award to recognize the top offensive players in each league. He was awarded the Presidential Medal of Freedom in 2002. He was named a 2010 Georgia Trustee by the Georgia Historical Society in recognition of accomplishments that reflect the ideals of Georgia's founders. Aaron resided near Atlanta until his death.