Leopold Eidlitz (March 10, 1823,Prague, Bohemia – 1908, New York City) was a prominent New York architect best known for his work on the New York State Capitol (Albany, New York, 1876–1881), as well as "Iranistan" (1848), P. T. Barnum's house in Bridgeport, Connecticut; St. Peter's Church, on Westchester Avenue at St. Peter's Avenue in the Bronx (1853); the Brooklyn Academy of Music on Montague Street in Brooklyn (1861, destroyed by fire 1903); the former Temple Emanu-El (New York, 1866–68, destroyed 1927); the Broadway Tabernacle (1859, demolished about 1907); the completion of the Tweed Courthouse (1876–81); and the Park Presbyterian Chapel on West 86th Street and Amsterdam Avenue.
Eidlitz was born in Prague into a Jewish family; his parents were Abraham and Judith Eidlitz, and he had one brother Markus (later Marc) Eidlitz. He received his early technical training at the Prague Realschule and then continued his education at the Vienna Technical University. He enrolled in its short-lived business school, not its engineering or architecture curricula. Eidlitz emigrated from Vienna to the United States in 1843 and settled in New York. His brother Marc Eidlitz emigrated to New York three years later.
Eidlitz spent three formative years in the office of Richard Upjohn. He likely participated in his project of constructing Trinity Church at the head of Wall Street, which was under way. He also worked with the architect Cyrus Lazelle Warner, whose office was a few doors from that of Upjohn's.