Karl Heinrich Leopold Deschner (23 May 1924 – 8 April 2014) was a German researcher and writer who achieved public attention in Europe for his trenchant and fiercely critical treatment of Christianity in general and the Catholic Church in particular, as expressed in several articles and books, culminating in his 10 volume Christianity's Criminal History (Kriminalgeschichte des Christentums, Rowohlt Verlag, Reinbek).

Initially matriculating as a major in Forestry in the University of Munich, Deschner attended lectures on Law, Theology, Philosophy and Psychology during 1946/47 at the Philosophical-Theological College in Bamberg.

From 1947 to 1951 at the University of Würzburg he studied Contemporary German Literature, Philosophy and History and graduated in 1951 with a doctoral dissertation entitled Lenau's Lyrics As an Expression of Metaphysical Despair.

From 1924 to 1964, Deschner resided in a former hunting lodge of the prince-bishops of Tretzendorf (Steigerwald), then for two years in the country house of a friend in Fischbrunn (near Hersbruck, Franconian Jura).

Outside of Germany, his works remained largely unpublished until the eighties, when translated versions (where necessary) were published in Spain, Switzerland, Italy and Poland.

The German entrepreneur Herbert Steffen, founder of the humanistic Giordano Bruno Foundation has continued to support Deschner's work.

In June 1993 he followed Walter Jens, Dieter Hildebrandt, Gerhard Zwerenz and Robert Jungk in winning the Alternative Büchner Prize and in July 1993, following Andrei Sakharov and Alexander Dubček, he was the first German to be recognized with the International Humanist Award.