Richard Gregory Rieker
- Height 6' 2", Weight 230 lb.
Born in St. Louis, MO in 1961, he umpired in the Midwest League in 1983 and 1984, and then moved to the Eastern League in 1985. He umpired his first major league game as a National League umpire in mid-season in 1992 but did not become part of a regular umpiring crew until 1996. In between, he was a substitute umpire. He umpired in two Division Series and in the 1998 All-Star Game. He retired mid-way through the 2001 season, then in 2002 was hired by MLB to serve as a liaison with major league umpires.
Rieker has been active in umpire development with MLB. He coordinated the annual MLB umpire camp starting in 2006 and worked with the international umpires who officiated the first two editions of the World Baseball Classic. He has also been an instructor at the Harry Wendelstedt umpire school. In 2011, he was promoted to Director of Umpiring, alongside Randy Marsh.