| Gideon Brecher | |
| Birth Date: | 12 January 1797 |
| Birth Place: | Prossnitz, Moravia, Habsburg Empire |
| Death Place: | Prossnitz, Moravia, Austria-Hungary |
| Alma Mater: | University of Erlangen |
| Spouse: | Josephine Zadek |
| Relatives: | Moritz Steinschneider (nephew) |
Gideon Brecher (; 12 January 1797 – 14 May 1873), also known by the pen name Gedaliah ben Eliezer (was an Austrian writer and physician. He was a central figure in the Moravian Haskalah.
Brecher was born in Prossnitz, Moravia, and attended yeshivot in Eibenschütz and Nikolsburg. He was the first Jew of Prossnitz to study medicine or any other professional field. Brecher received a graduate degree in surgery and obstetrics at the University of Pest in 1824, and obtained a doctorate in medicine at the University of Erlangen in 1849, with the thesis Das Transcendentale, Magie und Magische Heilarten im Talmud (Vienna, 1850).
Brecher's fame in Jewish literature rests principally on this work and upon his lucid commentary on the Kuzari of Judah ha-Levi, which appeared with the text in four parts (Prague, 1838–1840). His correspondence with Samuel David Luzzato about this commentary was also published.
In addition to many contributions to scientific and literary periodicals and collections, and some important "Gutachten" (expert opinions) on social and religious questions submitted to him by imperial and local government officials, Brecher is the author of a monograph on circumcision, Die Beschneidung der Israeliten (Vienna, 1845), with an introduction by Hirsch Fassel, and an appendix on Circumcision Among the Semitic Nations, by Moritz Steinschneider. Brecher also wrote Die Unsterblichkeitslehre des Israelitischen Volkes (Vienna, 1857), of which a French translation appeared in the same year by ; and Concordantiæ nominum propriorum, a concordance of Biblical proper names, part of which was revised and published after his death by his son Adolph Brecher.