Spanish politician and historical leader of the Partido Comunista de España (PCE/Communist Party of Spain). Son of Wenceslao Carrillo, leader of the Spanish Socialist Worker's Party (Partido Socialista Obrero Español/PSOE) and the Unión General de Trabajadores (UGT/General Union of Workers) that in the twenties, when Santiago was nine years old, moved from Asturias to Madrid to join the editorial office of the journal El Socialista. He studied in the Cervantes School Group in the neighborhood of Cuatro Caminos, but soon he was forced to leave school to work as a printer's apprentice. At the age of thirteen, he joined UGT and the Socialist Youth of Madrid. In 1930 he began to collaborate in El Socialista, where he was in charge of the parliamentary report after the proclamation of the Second Republic. In the IV National Congress of the Socialist Youth, celebrated in February 1932, he was elected secretary of acts of the Executive Committee, taking charge in 1933 of the direction of his press body, the weekly newspaper Renovación. At the beginning of that year he joined the Socialist Association of Madrid. The V Congress of Socialist Youth gathered in April 1934 elected Carrillo as Secretary of the Executive Committee. He participated in the October Revolution of 1934, being arrested and imprisoned in the Model Prison of Madrid where, together with Carlos Hernández Zancajo and Amaro Rosal Díaz, he wrote October: second stage (1935); he defends the 'Bolshevization' of PSOE. The triumph of the Frente Popular (Popular Front) in February 1936 led to an amnesty, thanks to which Carrillo left prison. He was one of the main architects of the creation of the Juventudes Socialistas Unificadas (JSU/Unified Socialist Youth), from the unification of the Socialist and Communist Youth, in April 1936, and being appointed Secretary‑General. During the negotiations, he headed a youth delegation that visited the USSR. This was a trip from which he returned impregnated by the communist ideology, although his entry into the PCE would not be formalized until November 1936. At that time he took over the Ministry for Order Public of the Madrid Defense Board, remaining in that position until 24 December 1936. Under his government, the executions of the prisoners of the Madrid prisons in Paracuellos del Jarama during their transfer to Valencia took place, in order to prevent them being released before what seemed as the imminent capture of Madrid by the rebel troops. In 1937 Carrillo was part of the PCE Central Committee and he was an alternate member of his Political Bureau. He continued at the head of the General Secretariat of the JSU until June 1947. With the fall of Barcelona, he was exiled into France, traveling later to Belgium, the Soviet Union, Cuba, Mexico, Algeria, and again to France, where he was in charge of the reorganization of the PCE on the inside. In May, 1939 he addressed a stern letter to his father, breaking off relations with him and accusing him of treason against the working class because of his involvement in the National Defense Council at the end of the Spanish Civil War. In 1942 he was appointed as titular member of the Political Bureau of the PCE and in 1946-1947 he was minister without portfolio of the Government of the Republic in exile directed by Giral. He took charge of the General Secretariat of the PCE at the VI Congress held in 1960, replacing Dolores Ibarruri, who assumed the presidency of the party. From 1962, the discrepancies between Carrillo and other leaders of the PCE began, specifically Fernando Claudín, Jorge Semprún and Javier Pradera. All three were expelled from the party in March 1964. They were accused of 'petty bourgeois' and 'social democrats' for their disagreements with the party leadership regarding the lack of internal debate and the pursuit of the USSR. After the Soviet invasion of Czechoslovakia in 1968, which Carrillo and the PCE expressly condemned, he begun to separate from the line marked by the Communist Party of the Soviet Union (CPSU). Years later he became one of the main drivers of the Eurocommunism. The condemnation of the invasion of Czechoslovakia helped to accredit the communist's 'Pact for Freedom' policy. With the aim of ensuring the role of the PCE in the post‑Franco period, Carrillo organized a so-called 'Junta Democrática' (Democratic Council), germ of a future provisional government in charge of liquidating the Franco regime. Later, it was unified with the 'Platform' promoted by the PSOE and other minority groups. It is sometimes known as 'Platajunta'. In 1976 Carrillo began to make clandestine trips to Spain from Paris, until he was finally arrested in December of that year. He was released and expelled to France. Months later, the responsible attitude shown by the PCE militancy after the murder of a group of labor lawyers in Madrid, as well as the direct contact between Adolfo Suárez and Carrillo, facilitated the legalization of the PCE on 9 April 1977. On 14 and 15 April, the first legal meeting of the PCE Central Committee was held in Madrid since the Spanish Civil War. In it, the commitments assumed by Carrillo for the legalization of the communists were made public, including the acceptance of the bicolor flag, the Monarchy or the unity of Spain, without prejudice to the recognition of nationalities. He was elected deputy for Madrid in the 1977, 1979, and 1982 general elections. During the Constituent Assembly and first parliamentary terms he would form part of the Communist Parliamentary Group, moving to the Mixed Group as of 1979. After the electoral defeat in 1982, he resigned as Secretary-General of PCE in November of the same year, although he continued as parliamentary spokesperson until April 1985. In that year he was also excluded from the PCE Executive Committee and he constituted the Spanish Partido de los Trabajadores (Workers Party). The new party was defeated in the 1986 general elections and joined PSOE in 1991. Carrillo did not participate in the integration, retiring from politics. Since then, he was devoted to collaborate in radio and press. He died in Madrid on 18 September 2012.