Kortatu was a Basque group of music founded in Spain in 1984 by the sibilings Fermin (voice and and guitar) and Iñigo Muguruza (bass and chorus) with Mattin (drums), but he was later replaced by Treku Armendariz.They were the first ones in introduce ska in Spain (with a punk base). This kind of music generated a movement called Radical Basque Rock. The name of the group is the nickname of Manuel Mª Garmendia Zubiarrain, a mugalari (person who helped other people to cross the border between France and Spain) killed by the police. Their songs are both in Basque and in Spanish, and they were supporters of Basque nationalists.

Once they played in Martutene gaol with another group called Barricada, and a couple of months later the two ETA's members Joseba Sarrionandia e Iñaki Pikabea escaped inside a speaker during the concert of Imanol Larzabal, and Kortatu was accused of having organised it so they weren't allowed to play in any other gaol since then. Later they made their famous song "Sarri Sarri" dedicated to the jailbreak.

The group split up in 1988, and the Muguruza brothers created Negu Gorriak with Kaki Arkarazo.