William Roger Clemens, aka "The Rocket" (born August 4, 1962) is a former right-handed Major League Baseball pitcher. Clemens won seven Cy Young Awards, two more than any other pitcher. He played for 13 consecutive seasons in Boston, more than half of his career. In 1997, he signed with the Toronto Blue Jays. In each of his two seasons with the Blue Jays Clemens won the pitching triple crown (leading the league in wins, ERA, and strikeouts) and a Cy Young Award.

Clemens was traded to the New York Yankees for the 1999 season, where he had his first World Series success. In 2003, he reached his 300th win and 4,000th strikeout in the same game. Clemens is one of only four pitchers to have more than 4,000 strikeouts in their career (the others are pitchers Nolan Ryan, Randy Johnson, and Steve Carlton). Clemens played three seasons with the Houston Astros, where he won his seventh Cy Young Award. He rejoined the New York Yankees during the 2007 season.

Clemens was alleged by the Mitchell Report to have used anabolic steroids during his late career. He has firmly denied these allegations under oath before Congress, and is now under investigation by the Justice Department for perjury. On May 12, 2009, he broke a long silence to speak out on ESPN against "American Icon: The Fall of Roger Clemens and the Rise of Steroids in America's Pastime", a book by four New York Daily News investigative reporters that claims Clemens used performance-enhancing drugs during his career.