The Helvetic Republic (French: République Hélvetique, German: Helvetische Republik, Italian: Repubblica Elvetica) was a sister republic of France that existed between 1798 and 1803, during the French Revolutionary Wars. It was created following the French invasion and the consequent dissolution of the Old Swiss Confederacy, marking the end of the ancien régime in Switzerland. Throughout its existence, the republic incorporated most of the territory of modern Switzerland, excluding the cantons of Geneva and Neuchâtel and the old Prince-Bishopric of Basel.

The Swiss Confederacy, which until then had consisted of self-governing cantons united by a loose military alliance (and ruling over subject territories such as Vaud), was invaded by the French Revolutionary Army and turned into an ally known as the "Helvetic Republic". The interference with localism and traditional liberties was deeply resented, although some modernizing reforms took place. Resistance was strongest in the more traditional Catholic cantons, with armed uprisings breaking out in spring 1798 in the central part of Switzerland. The French and Helvetic armies suppressed the uprisings, but opposition to the new government gradually increased over the years, as the Swiss resented their loss of local democracy, the new taxes, the centralization and the hostility to religion. Nonetheless, there were long-term effects.

The Republic's name Helvetic, after the Helvetii, the Gaulish inhabitants of the Swiss Plateau in antiquity, was not an innovation; rather, the Swiss Confederacy had occasionally been dubbed Republica Helvetiorum in humanist Latin since the 17th century, and Helvetia, the Swiss national personification, made her first appearance in 1672. In Swiss history, the Helvetic Republic represents an early attempt to establish a centralized government in the country.