Arthur Albert Irwin (February 14, 1858 – July 16, 1921), nicknamed "Doc", "Sandy", "Cutrate" or "Foxy", was a Canadian-American shortstop and manager in Major League Baseball (MLB) during the late nineteenth century. He played regularly in the major leagues for eleven years, spending two of those seasons as a player-manager. He played on the 1884 Providence Grays team which won the first interleague series to decide the world champions of baseball. Irwin then served as a major league manager for several years.

Irwin occupied numerous baseball roles in the latter years of his career, having spent time as a college baseball coach, a major league scout and business manager, a minor league owner and manager, and a National League umpire. For most of Irwin's career, the collegiate and professional baseball schedules allowed him to hold positions at both levels in the same year.

Irwin also produced several innovations which impacted sports. He took the field with the first baseball fielder's glove, invented a type of football scoreboard, promoted motor-paced cycling tracks and ran a short-lived professional soccer league.

Irwin became terminally ill with cancer in the last weeks of his life. Shortly after his death from an apparent suicide, Irwin made headlines when it was discovered that two wives and families survived him in separate cities. He had been married to one woman since the 1880s and to the other since the 1890s. He was posthumously elected to the Canadian Baseball Hall of Fame in 1989.