Ottaviano-Fabrizio Mossotti (18 April 1791 – 20 March 1863) was an Italian physicist who was exiled from Italy for his liberal ideas.

During the First Italian War of Independence he led a "battalion of students", part of a delegation from the Grand Duchy of Tuscany.

His studies on dielectrics led to important results: the Clausius-Mossotti formula is partly named after him, and his views on dielectric behavior helped lead James Clerk Maxwell to devise his theory of the displacement current, which led in turn to the theoretical prediction of electromagnetic waves.

[1] Mossotti was chair of experimental physics in Buenos Aires (1827–1835) and taught numerous Argentinian physicians his views on dielectrics, thereby becoming influential on the Argentine-German neurobiological tradition regarding electricity inside brain tissue.

Later (after 1906) these views influenced this tradition's models of stationary waves in the interference of neural activity for short-term memory.