Mary K. Buck (née Knížková; April 1, 1849 – December 28, 1901) was a Bohemian-born American author.

English books were rare in her family home, but the town library, of which she was a patron, was well stocked.

Early in life, she developed a talent for composition, especially of fiction, which was encouraged by her teachers and friends.

During the summer of 1891, she published, together with M. E. C. Bates, a book of short sketches entitled Along Traverse Shores.

She contributed to the Congregationalist, the Advance, the Chicago Inter Ocean , the Portland Transcript, Good Housekeeping, St. Nicholas, and many other periodicals.