Kilian Ignaz Dientzenhofer, Bohemian architect, designed Ss. Cyril and Methodius Cathedral (d. 1751)
Kilian Ignaz Dientzenhofer (Czech: Kilián Ignác Dientzenhofer) (1 September 1689, Prague – 18 December 1751) was a Bohemian architect of the Baroque era. He was the fifth son of the German architect Christoph Dientzenhofer and the Bohemian-German Maria Anna Aichbauer (née Lang), widow of the architect Johann Georg Achbauer the Elder, and a member of the well known Dientzenhofer family of architects. As an architect he co-operated with his father and with Jan Santini Aichel.

Among Dientzenhofer's Prague buildings are the churches of Saint John of Nepomuk and Saint Nicholas, as well as the Vila Amerika and the Kinský Palace. He also built numerous churches and secular buildings in other towns of Bohemia. Many of his later projects were realized by his pupil and son-in-law Anselmo Martino Lurago.