Robert Allen Engel (October 11, 1933 – March 5, 2018) was an American professional baseball umpire who worked in the National League from 1965 to 1990. Engel wore uniform number 5 for most of his career. A former president of the umpires union, Engel retired after being arrested for the theft of more than 4,000 baseball cards from a Target store in California, for which he pleaded no contest.