Trebbiano is a white grape used to make white wine, and the most common white grape variety in Italy, accounting for around a third of all Italy's white wine. It is cited in over 80 of Italy's DOCs.

The grape is known as Ugni Blanc in France, where it is also the most widely planted white grape. In France the grape is also sometimes known as Clairette Ronde, in Bulgaria and Portugal is called Thalia, and in Corsica as Rossola. In total the variety almost certainly produces more white wine than any other grape in the world.

The name, in fact, covers a collection of almost indistinguishable varieties, all of which are known for their bland flavour and high acidity. The most important sub-varieties include Trebbiano di Soave, Trebbiano Toscano, Trebbiano Romagnolo, Trebbiano Gallo and Trebbiano d'Abruzzo.

Despite its ubiquitous nature, the wine produced by the grape is overly acidic and usually flavourless, and so requires great skill to make it into a desirable table wine. However, its high acidity makes it useful for making brandy and is thus the most widely used variety of the Cognac and Armagnac regions.