
Hans Beimler was a trade unionist, Communist-Party official, deputy in the 1933 Reichstag, an outspoken opponent of the Nazis and a volunteer in the international brigades fighting for the Spanish Republic.

Julian Heward Bell was an English poet, and the son of Clive and Vanessa Bell. The writer Quentin Bell was his younger brother and the writer and painter Angelica Garnett was his half-sister. His relationship with his mother is explored in Susan Sellers' novel Vanessa and Virginia.

Federico Borrell García was a Spanish Republican and anarchist militiaman during the Spanish Civil War, commonly thought to be the subject in the famous Robert Capa photo The Falling Soldier.

George Brown was an Irish born communist activist and trade unionist who was based in Manchester, England for most of his life. He was a brigadista in the International Brigades fighting on the Republican side in the Spanish Civil War and was killed in the Battle of Brunete in 1937.

Christopher Caudwell was the pseudonym of Christopher St John Sprigg, a British Marxist writer.

Lewis Clive was a British rower who won a gold medal in the 1932 Summer Olympics. He volunteered to fight for the Republicans in the Spanish Civil War and was killed in action.

Rupert John Cornford was an English poet and communist. He was the son of Francis Cornford and Frances Cornford, and was a great-grandson of Charles Darwin and Emma Darwin. During the first year of the Spanish Civil War, he was a member of the POUM militia and later the International Brigades. He died while fighting against the Nationalists, at Lopera, near Córdoba.

Louis Émile Cottin was a French militant anarchist who is best known for the attempted assassination of Georges Clemenceau.

Peter Daly was an Irish Socialist and Republican who fought in the Irish War of Independence as well as serving as a volunteer in the Spanish Civil War, where he died serving with the International Brigades.

Francesco Del Grosso was an Italian cyclist. He competed in two events at the 1924 Summer Olympics. He was killed fighting for the Nationalist faction during the Spanish Civil War.

Carmelo Delgado Delgado was a leader of the Puerto Rican Nationalist Party. Delgado joined the Abraham Lincoln International Brigade and fought against the Spanish Nationalists in the Spanish Civil War. Delgado Delgado, a Puerto Rican by birth and national origin, is thought to be the first U.S. citizen to die in Spain's civil war.

Charles Patrick "Charlie" Donnelly was an Irish poet, republican and left wing political activist. He was killed fighting on the republican side during the Spanish Civil War.

José Buenaventura Durruti Dumange was a Spanish insurrectionary, anarcho-syndicalist militant involved with the CNT, FAI and other anarchist organisations during the period leading up to and including the Spanish Civil War. Durruti played an influential role during the Spanish Revolution and is remembered as a hero in the anarchist movement.

Mikalai Dvornikau known under the pseudonyms Gerasim, Andrei, Anton, Stanislav Tomashevich, Robert and Petya was a Soviet Belarusian political militant, a member of the Communist Party of Western Belarus and the Communist Youth League (Komsomol) of Western Belarus. He was a participant of the Spanish Civil War, political instructor of the Jose Palafox battalion and commander of the Ukrainian interbrigade company Taras Shevchenko.

Ralph Winston Fox (1900-1936) was a British revolutionary, journalist, novelist, and historian, best remembered as a biographer of Lenin and Genghis Khan. Fox was one of the best-known members of the Communist Party of Great Britain (CPGB) to be killed in Spain fighting against the Nationalists in the Spanish Civil War.
Ramón Franco Bahamonde, was a Spanish pioneer of aviation, a political figure and brother of later caudillo Francisco Franco. Well before the Spanish Civil War, during the reign of Alfonso XIII, both brothers were acclaimed as national heroes in Spain; however, the two had strongly differing political views. They had a less-known brother, Nicolás.

Primo Gibelli was an Italian Communist, immigrant to the Soviet Union, and fighter pilot who was awarded the title Hero of the Soviet Union after his death in the Spanish Civil War.

David Guest was a British mathematician and philosopher who volunteered to fight for the Republicans in the Spanish Civil War and was killed in Spain in 1938.

Robert Martin Hilliard was an Olympic boxer, Irish republican, Church of Ireland minister and communist. He was killed in the Spanish Civil War fighting in the International Brigades.

Oliver Law was an African-American communist and labor organizer, who fought for the Republic in the Spanish Civil War. He was the commander of the entire Abraham Lincoln Brigade for several days and commander of its Machine Gun regiment for much longer.

Vasile Marin was a Romanian politician, public servant and lawyer. A member of the National Peasants' Party until 1932, Vasile Marin later became a prominent member of the Romanian fascist organisation, the Iron Guard. His death in the Spanish Civil War as a volunteer for the Nationalists alongside the death of fellow volunteer and Iron Guard leader, Ion Moța is credited with contributing to the growth of the Iron Guard.

Robert Hale Merriman was an American doctoral student who fought with the Republican forces in Spain during the Spanish Civil War. He was killed while commanding the Abraham Lincoln Battalion of the International Brigades.

Ion I. Moța was the deputy leader of the Romanian fascist Legionary Movement, killed in battle during the Spanish Civil War.

Božidar "Boško" Petrović was a Yugoslav fighter ace of the Spanish Civil War and professional footballer.

Colonel Ildefonso Puigdendolas Ponce de Leon was a Spanish military officer who served the Republic during the Spanish Civil War. In 1931 he was colonel of Infantry in Seville as inspector of the security corps. In 1934 he was appointed to Malaga. In July 1936 he defeated the rebels forces at Alcala de Henares and Guadalajara. After that, he commanded the Loyalist militia at the Battle of Badajoz in 1936. After the battle of Badajoz he escaped to Portugal and returned to the zone controlled by the Spanish Republican Army. During the battle of Seseña Puigdendolas was killed by his own men when trying to prevent desertion.
Onésimo Redondo Ortega was a Spanish Falangist politician. He founded Juntas Castellanas de Actuación Hispánica, a political group that merged with Ramiro Ledesma's Juntas de Ofensiva Nacional-Sindicalista and José Antonio Primo de Rivera's Falange Española.

John Pascal Rickman (1910–1937) was a British communist activist who was killed during the Spanish Civil War. Before the war, he dropped out from Lincoln College of the University of Oxford, and became an expert on English church architecture, took part in the Battle of Cable Street, and became involved in various religious and political organisations which aimed to better the conditions of the working class, including the Communist Party of Great Britain (CPGB).

Hernando Carlos María Teresa Fitz-James Stuart y Falcó, 18th Duke of Peñaranda de Duero, GE, was a Spanish nobleman.

Yuri Dmytrovych Velykanovych (ukr. Ю́рій Дми́трович Великано́вич; 1910, Turka, Galicia, Austria-Hungary, September 7, 1938, Ebro Valley, Spanish Republic) was a participant in the Spanish Civil War, Ukrainian interbrigadist, member of the Communist Party of Western Ukraine (CPWU).