From the Wikipedia page 
Also referred to as Raphael Mnishovsky and Raphael Mischowsky de Sebuzina: full name Raphael Sobiehrd-Mnishovsky of Sebuzin and of Horstein (1580 – 21 November 1644)
A Bohemian lawyer and writer, who held various secretarial, diplomatic, and judicial posts under Rudolf II, Mathias, Ferdinand II, and, Ferdinand III, under whom Raphael was the attorney-general. (See Wikipedia for biographies of the non-VM related persons.)
Mnishovsky was also a poet and cryptographer /, and is linked to the Voynich Manuscript. According to a 1666 letter which was stored with the manuscript, Raphael had told the letter's writer, Jan Marcus Marci, that the manuscript had originally belonged to Rudolf, who had purchased it for 600 gold ducats.
Apparently invented an uncrackable cipher.
More information here