Augusto Barcia y Trelles (Vegadeo, 1881 – Buenos Aires, 1961) was a Spanish politician, several times member of the Congress of Deputies, who served as acting Prime Minister of Spain from 10 May 1936 to 13 May 1936 due to former PM Manuel Azaña being elected as President of the Republic. He was also a lawyer and a Freemason.
As a member of the Spanish Cortes he was firmly against the Antiterrorist Act pushed in 1908 by then-PM Antonio Maura. He was also a member of the Cortes from 1916 to 1923, when they were finally dissolved by Primo de Rivera's dictatorship. During the Second Republic he affiliated himself with the Republican Left, and was elected to the Congress of Deputies in the 1936 elections. He defended Lluís Companys and his colleagues of the Catalan Generalitat over their participation in the rising against the Republic of October 1934. After the triumph of the Popular Front in the elections of February 1936, he was named minister of State in the governments of Manuel Azaña, Santiago Casares Quiroga, Diego Martínez Barrio and José Giral. He was also the 255th and 25th Minister of Foreign Affairs between 19 February 1936 and April 1936 and between 19 July 1936 and 4 September 1936, respectively. After the end of the Spanish Civil War he fled to Argentina.