Mariano Rivera (born November 29, 1969) is a Panamanian right-handed baseball pitcher who has played 17 years in Major League Baseball (MLB) for the New York Yankees. Nicknamed "Mo", Rivera has served as a relief pitcher for most of his career, and since 1997, he has been the Yankees' closer. A 12-time All-Star and five-time World Series champion, Rivera ranks first in MLB history in games finished (880) and saves (601). His achievements include winning the American League (AL) Rolaids Relief Man Award five times, the 1999 World Series MVP Award, and the 2003 AL Championship Series MVP Award.

Rivera was signed by the Yankees organization in 1990 as an amateur free agent in Panama, and he debuted in the major leagues in 1995. Initially a starting pitcher, he struggled in the role and was consequently converted to a relief pitcher. After a breakthrough season in 1996 as a setup man, he became the Yankees' closer in 1997. In the following years, he established himself as one of baseball's top relievers, leading the major leagues in saves in 1999, 2001, and 2004. His presence in the late innings of games to record the final outs has played an instrumental role in the Yankees' success in the late-1990s and 2000s. His pitching repertoire consists primarily of one pitch—a sharp-breaking, mid-90s mile per hour (mph) cut fastball that has been called an all-time great pitch.

Rivera is regarded as one of the most dominant relievers in baseball history. Pitching with a longevity and consistency uncommon to the closer role, he has saved at least 25 games in a record 15 consecutive seasons and has posted an earned run average (ERA) under 2.50 in 12 seasons. Rivera has further distinguished himself with a calm, placid demeanor that contrasts with the demonstrative nature of many of his peers. An exceptional postseason performer, he holds postseason records for saves (42) and ERA (0.71), among other records. Sportswriters anticipate Rivera will be inducted into the Baseball Hall of Fame upon retirement. He intends to work in philanthropy after his baseball career.