Eustaquio Echave-Sustaeta Pedroso (1872-1952) was a Spanish Carlist publisher and politician. He was related to numerous periodicals, but is known mostly as manager and editor-in-chief of the local Pamplonese daily, El Pensamiento Navarro (1897-1917). His career in party ranks climaxed in the early 1930s, when very briefly he held the Carlist provincial jefatura in Álava. The apogee of his political trajectory fell on early period of the Civil War, when he was president of the Alavese Diputación Provincial (1936-1938) and leader of Falange Española Tradicionalista in Álava (1937). At times he is also acknowledged as a polemist of Sabino Arana (mid-1890s), who inadvertently helped the latter to refine his theory of Basque nationalism, and as a point of reference for the Carlist position towards fueros.

Traditionalism is a Spanish political doctrine formulated in the early 19th century and developed until today. It understands politics as implementing the social kingship of Jesus Christ, with Catholicism as the state religion and Catholic religious criteria regulating public morality and every legal aspect of Spain. In practical terms it advocates a loosely organized monarchy combined with strong royal powers, with some checks and balances provided by organicist representation, and with society structured on a corporative basis. Traditionalism is an ultra-reactionary doctrine; it rejects concepts such as democracy, human rights, constitution, universal suffrage, sovereignty of the people, division of powers, religious liberty, freedom of speech, equality of individuals, and parliamentarism. The doctrine was adopted as the theoretical platform of the Carlist socio-political movement, though it appeared also in a non-Carlist incarnation. Traditionalism has never exercised major influence among the Spanish governmental strata, yet periodically it was capable of mass mobilization and at times partially filtered into the ruling practice.