Nancy Share Rapp (d. 2002) was a science fiction fanzine editor and artist.
Nancy Share began publishing fanzines with her sister Marie-Louise Share. Together they produced Hodge Podge in the early 1950s. The 4th issue, appearing in December 1953, was 30 pages, and by the 11th issue, appearing in September 1954, it had increased to 48 pages. Eleven issues were released.
Her next zine was Ignatz, also published in the 1950s. At least 19 issues were released, with no. 18 recorded as appearing October 1958, and no. 19 in January 1959. Issues 18 and 19 are included in the Fanzine Collection of Temple University Library.
Nancy Share is credited with originating many catch-phrases that have been popular in science fiction fandom. She is credited with popularizing the term "Ignatz', through her zine of the same name in the 1950s. She is credited with the definition of the term "Filk Song", a singing style popular with SF enthusiasts. As well, in SF fandom the catch phrase "Bitcher Knife" is associated with Nancy Share, as in "don't provoke Nancy Share to use her Bitcher Knife on you".