Konrad Kyeser (26 August 1366 – after 1405) was a German military engineer, author of Bellifortis (c.
1405), a book on military technology popular throughout the 15th century.
Originally conceived for King Wenceslaus, Kyeser dedicated the finished work to Rupert of Germany.
Kyeser, a native of Eichstätt, was trained as a physician and lived at the court in Padua before he joined the crusade against the Turks which ended in disaster at the Battle of Nicopolis of 1396.
Kyeser was in exile in a mountain village of Bohemia during the reign of Sigismund in 1402 to 1403.