Lois Pérez Castrillo became Mayor of Vigo on 3rd July 1999 after the municipal elections and being at the top of the list of candidates presented by the political party 'BNG'. He studied Teaching at the Seminary in Vigo and became a teacher of Primary Education. Lois Pérez entered the political party BNG in 1986. During the period 1991-95, he was on the municipal government as councillor responsible for citizen participation. In this period, they presented the regulation about citizen participation, which is the most advanced one. He is on the National Committee of the political party BNG and was the president of the Union of villages within the area of Vigo, ProVigo Foundation and the executive committee of the Fair Union Institute of Vigo.
He collaborated in the magazine 'O Ensino' and carried out different works for the Galician Psychopedagogical Association.