Harry Stephen Ackerman (November 17, 1912 – February 3, 1991) was a prolific producer in American television and is credited with creating or co-creating a total of twenty-one television series, seven of which were at one time being broadcast simultaneously. Some of the sitcoms in which he was involved in production during the 1950s and 1960s are also among the most popular American shows in the early history of the “small screen”, such as "Father Knows Best", "Dennis the Menace", "Leave It to Beaver", "Hazel", "Bewitched", "The Flying Nun", and "Gidget".