William Richard Mueller (/ˈmɪlər/ MIL-ler; born March 17, 1971) is an American retired professional baseball third baseman who played in Major League Baseball (MLB). Mueller's MLB playing career was spent with the San Francisco Giants (1996–2000, 2002), Chicago Cubs (2001–2002), Boston Red Sox (2003–2005), and Los Angeles Dodgers (2006). He is currently the hitting coach at Arizona State.