Karen Brahe (born 1 December 1657 at Næsbyholm, died 27 September 1736 at Østrupgård, Haastrup parish), was a Danish aristocrat and book collector.
In 1681, she inherited the library of her maternal grandfather's sister, Anne Gøye (1609–81), daughter of Henrik Giøe of Skørringe and Turebygård.
[2] On 8 November 1716, she founded the Odense adelige jomfrukloster, a Lutheran collegiate foundation for unmarried noblewomen (now part of St. Catherine's Priory, Roskilde), which received royal confirmation on March 15, 1717.
Among the famous books held by the library are the ballad collections Karen Brahes Folio (shelfmark E I,1) and Jens Billes visebog (E I,2); the only manuscript of Leonora Christina Ulfeldt's Heltinders Pryd (C V,1); and a rare first edition of Margrethe Lasson's Den beklædte sandhed.
In 1987, the Karen Brahe Society was founded with the aim of establishing a women's cultural center in the monastery buildings, now owned by Odense Municipality.