Robert Lewis Thomson (born August 16, 1963), nicknamed "Topper", is a Canadian professional baseball manager for the Philadelphia Phillies of Major League Baseball (MLB).

During Thomson's playing career, he was a catcher and third baseman in the Detroit Tigers organization from 1985 to 1988. Following his years as a player, Thomson spent one year as the manager of the Class A Oneonta Yankees, and several more years in various front office capacities for the New York Yankees organization. He then served as the Yankees’ bench coach in 2008, third base coach from 2009 to 2014, and bench coach again from 2015 to 2017.

In 2018, Thomson was hired as the bench coach of the Philadelphia Phillies. On June 3, 2022, Thomson was named interim manager of the Philadelphia Phillies following the firing of manager Joe Girardi. After leading the Phillies to their first postseason appearance since 2011, Thomson was named the full-time manager on October 10, 2022. That year, he went on to lead the Phillies to their first National League pennant since 2009. Thomson has led the Phillies to four postseason appearances and two National League East titles in his four seasons with the team.

Thomson was born on August 16, 1963, in Sarnia, Ontario, and grew up in nearby Corunna, Ontario. He grew up playing baseball in the summers and hockey in the winter. Thomson has a younger sister and two older brothers, one of whom signed with the Montreal Expos.

Thomson was a standout for the Stratford Nationals of the Intercounty Baseball League. From there, he was recruited to St. Clair County Community College where he played baseball for one year. After a year, he transferred to the University of Kansas. Thomson led the Jayhawks in hits in 1984 and 1985 and holds the school record for the highest single-season batting average.

Thomson was selected by the Detroit Tigers in the 32nd round of the 1985 Major League Baseball draft from the University of Kansas. He played catcher and third base in the Tigers' minor league system until 1988, reaching as high as Class A. In 661 at bats, he hit .225/.312/.304 with seven home runs and three steals. He played 136 games at catcher, 55 games at third base, and pitched in one game.

Thomson represented Canada in baseball, which was a demonstration sport, in the 1984 Summer Olympics in Los Angeles.

From 1988 to 1990, Thomson served as a minor league coach in the Detroit Tigers organization. Thomson says he got into coaching because "I wasn’t a good enough player. The game sort of forced me into coaching. I was lucky enough the Tigers thought enough of me as an evaluator, teacher and an organizer to offer me a coaching position."