Gaillac (French pronunciation: [ɡajak] ⓘ; Occitan: Galhac) is a commune in the Tarn department in southern France.

The town was founded in the second century CE by the Gauls who created a river port where they exported their wine into Gallia Narbonensis.

It was only when the monks of Saint-Michel gained viticulture privileges from the Bishop of Albi, in 972, that the population stabilized and Gaillac started to become a town again.

During the religious wars, the "Gaillacois" refused to change their religion and remained Catholics and were chased out of the town by Protestants.

It was from the town of Gaillac that Louis-Philippe I addressed the words: Nous chercherons à nous tenir dans un juste milieu, également éloigné des excès du pouvoir populaire et des abus du pouvoir royal.