Roussillon (Catalan Rosselló) is one of the historical Catalan counties corresponding roughly to the present-day southern French département of Pyrenées-Orientales (Eastern Pyrenees). It is as well called French Catalonia, but only a minority (40%) of its inhabitants now speak Catalan and only a 60% understand the language.
One of the counties ruled by the count of Barcelona since 872, Roussillon (along with the rest of Catalonia), it entered the kingdom of Aragon from 1137, when the Count of Barcelona became the King of Aragón. From 1276 until 1344 Roussillon's principal city Perpignan was the capital of the kingdom of Majorca. Part of the kingdom of Spain from 1479, Roussillon was occupied by France in 1642 and ceded by Spain in the Treaty of the Pyrenees (1659).
Roussillon gave its name to the French région Languedoc-Roussillon.
Roussillon is also the name of a commune in the Vaucluse département in France.