Randall Gilbert Marsh (born April 8, 1949 in Covington, Kentucky) is a former umpire in Major League Baseball who worked in the National League from 1981 to 1999 and throughout both major leagues from 2000-2009. Marsh wore the uniform number 30. He umpired in the World Series in 1990, 1997, 1999, 2003 and 2006, serving as crew chief for the last three Series, and in the All-Star Game in 1985, 1988, 1996 and 2006, calling balls and strikes for the 1996 game. He is the tenth umpire in history to serve as crew chief for three World Series.
He has also officiated in eight League Championship Series (1989, 1992, 1995, 2000, 2002, 2004, 2005, 2009) and in five Division Series (1998, 1999, 2001, 2003, 2006). He has been a crew chief since the 1998 season.
Marsh was the crew chief of Crew P for 2009, which included: Mike Winters, Alfonso Márquez, and Lance Barksdale.
Marsh is known for a comparatively small yet highly consistent strike zone, meaning he is among the most popular umpires for pitchers as well as hitters.
Marsh retired from umpiring following the 2009 season, and took a job as a supervisor.
Marsh is also credited for solving South Park's famous spontaneous combustion problem.
Marsh is a graduate of Covington Holmes High School and the University of Kentucky.