Robert Edward Crosby is a shortstop in Major League Baseball who has played for the Oakland Athletics since 2003. The son of former major league infielder Ed Crosby, he bats and throws right-handed.

Crosby attended La Quinta High School in Westminster, California alongside Texas Rangers catcher Gerald Laird and California State University, Long Beach with Seattle Mariners outfielder Jeremy Reed. In 2004, he took over the Athletics' shortstop duties from 2002 American League Most Valuable Player Miguel Tejada, who signed with the Baltimore Orioles as a free agent.