Frommann is a German surname. Spelling variants include Fromman, Fromann, Fromman, Froman. (Especially people who emigrated to the United States simplified the spelling and got rid of the second "n".)
The name seems to have mainly spread from the German state Thuringia ("Thüringen"), and some branches of the family later moved to Saxe-Coburg ("Sachsen-Coburg"), and then further to the Nuremberg area, Württemberg/Swabia and other regions. Frommanns also emigrated to the USA, mostly taking the route Hamburg-New York.
Noteable people of this name include a prestiguous bookseller in the city of Jena who often was a host to Goethe, or famous professors of jurisprudence in Tübingen (Württemberg).
Andreas Frommann was awarded a coat of arms.