Johann Caspar von Orelli (13 February 1787–6 January 1849), was a Swiss classical scholar.
He was born at Zürich of a distinguished Italian family which had taken refuge in Switzerland at the time of the Protestant Reformation. His cousin, Johann Conrad Orelli (1770–1826), was the author of several works in the department of later Greek literature.
From 1807 to 1814 Orelli worked as preacher in the reformed community of Bergamo, where he acquired the taste for Italian literature which led to the publication of Contributions to the History of Italian Poetry (1810) and a biography (1812) of Vittorino da Feltre, his ideal of a teacher.
In 1814 he became teacher of modern languages and history at the cantonal school at Chur; in 1819, professor of eloquence and hermeneutics at the Carolinum, Zürich, and in 1833 professor at the new University of Zürich, the foundation of which was largely due to his efforts. His attention during this period was mainly devoted to classical literature and antiquities. He had already published (1814) an edition, with critical notes and commentary, of the Antidosis of Isocrates, the complete text of which, based upon the manuscripts in the Ambrosian and Laurentian libraries, had been made known by Andreas Mustoxydis of Corfu.
The three works upon which his reputation rests are the following:
He was a most liberal-minded man, both in politics and religion, an enthusiastic supporter of popular education and a most inspiring teacher. He took great interest in the struggle of the Greeks for independence, and strongly favoured the appointment of the notorious David Strauss to the chair of dogmatic theology at Zürich, which led to the disturbance of September 6, 1839 and the fall of the liberal government.