Koldo Gorostiaga Atxalandabaso (born 30 May 1940) is a Spanish Basque university lecturer in law and economics, and politician. He served one term in the European Parliament from 1999 to 2004 as a representative of Batasuna, a Basque nationalist party.

Gorostiaga was born in Bilbao^[1] and educated at the University of Valladolid and the University of Deusto, earning a law degree in 1963. He obtained a Doctor of Laws from the University of Barcelona in 1966, and later obtained a certificate of proficiency in English from Cambridge University. He has worked as a lecturer at the University of Barcelona and the University of Pau. He is also a Professor of the Basque Summer University, and a Professor and founding Director of the Cooperative Institute for Law and Social Economy at the University of the Basque Country.^[2]

Living mostly in the French Basque Country, Gorostiaga began working for the European Bureau for Lesser-used Languages in 1995, and also became a member of the Basque Country's Economic and Social Council.^[3] At the 1999 European Parliament election, Gorostiaga was nominated as Euskal Herritarrok candidate. He was elected to the last seat.^[4]