Stupinigi (Italian: [stupiˈniːdʒi]; Piedmontese: Stupinis [stypiˈniz]) is a frazione (hamlet/borough) of the comune (municipality) of Nichelino, in the Metropolitan City of Turin (Piedmont, north-west Italy).
Historically Stupinigi centres on the Castelvecchio: a medieval castle which belonged to the Savoy-Acaja [it], a branch of the House of Savoy who until 1416 were signori of Piedmont—a much smaller territory than the present-day region—and briefly Princes of Achaia.
In 1439, the castle was purchased by the Marquis Orlando Pallavicino (il Magnifico, "the Magnificent"); in 1563 it passed to the Duke of Savoy, Emmanuel Philibert, when the capital of the Duchy was transferred from Chambéry to Turin.
In 1832 ownership of the Palazzina passed to the royal family, in 1919 it became a property of the state and in 1925 it was returned to the Order, which retains it to this day.
The first reported introduction of grey squirrels in continental Europe occurred in 1948, when they were taken to Stupinigi, where there is still a growing population.