William Aalto — American poet and communist
Anton Ackermann — Leader of the Political School of the International Brigades.
Todor Angelov — Bulgarian anarcho-communist
Shapour Bakhtiar — last Prime Minister of Iran under the Pahlavi dynasty
Hans Beimler — After his death the XI International Brigade was named in his honour.
Norman Bethune — Canadian physician with the Mac-Paps
Herman Bottcher — two-time winner of the Distinguished Service Crosses during World War II
Willy Brandt—- West German Chancellor 1969–74; Nobel Peace Prize winner 1971; leader of the Socialist International 1976 – 1992
Ernst Busch — singer of broadcast battle songs - "Voice of the XI Brigade"
Robert Capa — Hungarian-born war photographer
Edward A. Carter, Jr. — American soldier who earned the Medal of Honor in World War II.
Fred Copeman — Royal Navy sailor
Vladimir Ćopić — 1937 commander of the XV International Brigade
John Cornford — British poet killed at Lopera, near Córdoba
Georgi Damyanov — Commander of the Albacete base under the nom de guerre of Colonel Belov
Carmelo Delgado Delgado — Puerto Rican nationalist
Charles Donnelly — poet
Ralph Winston Fox — British journalist
Janos Galicz — General "Gal"
Bill Gannon — Irish Republican and communist
Ermenegildo Gasperoni — Sammarinese communist, later head of state of San Marino
Pierre Georges — French communist
Nordahl Grieg — Norwegian writer
David Guest — British mathematician
Paul René Gauguin, painter and graphic designer, grandson of Paul Gauguin
Ernest Hemingway — author and war reporter
Jack Jones — political commissar of the Major Attlee Company of the XV International Brigade, later General Secretary of the Transport and General Workers' Union
James Robertson Justice — British actor
Ali Kelmendi — Albanian communist
Bernard Knox — English classicist; moved to the United States and joined the Army after the Civil War
František Kriegel — Czechoslovak politician
Arthur H. Landis — fantasy and non-fiction author, wrote Spain! The Unfinished Revolution, Order of Friendship of Peoples recipient
Oliver Law — African-American labor organizer and Abraham Lincoln Brigade commander
Laurie Lee — British poet
Tuure Lehén — Finnish communist and later Soviet general
Bert "Yank" Levy Jewish author of a handbook on guerrilla warfare, officer in the Saklatava Battalion, under Tom Wintringham
Luigi Longo — 1936 political commissar of Garibaldi Battalion, and 1937–38 of all International Brigades
Petro Marko — Albanian novelist (Hasta la Vista)
André Marty — Political commissar, nicknamed "Butcher of Albacete", later parliamentarian
Guido Nonveiller — Croatian professor
Ferenc Münnich (political commissar of Rakosi Battalion) became Chairman of the Council of Ministers of Hungary from 1958 to 1961.[48]
Conlon Nancarrow — American-born composer
George Nathan — Chief of Staff of the XV International Brigade from 1937
George Orwell — British writer and socialist[49]
Abe Osheroff — American activist
Randolfo Pacciardi — 1936–37 commander of the Garibaldi Battalion
Ezekias Papaioannou — Greek Cypriot communist and later general secretary of AKEL
Koča Popović — Yugoslav surrealist, Partisan Commander, General of the JNA, and Vice-President of Yugoslavia.
László Rajk — political commissar of the Rakosi Battalion; became Hungarian foreign secretary, was accused of espionage, and shot after a show trial in Hungary in 1949.[50]
Heinrich Rau — 1938 commander of the XI International Brigade
Ludwig Renn — German writer and 1936 commander of the Thälmann Battalion in the Battle of Madrid, then chief of staff XI International Brigade
Paul Robeson — troop entertainer/fundraiser/honorary member
Henri Rol-Tanguy — French communist
Valter Roman — Romanian communist
Esmond Romilly — English upper-class communist
Franc Rozman — Slovenian partisan general, national hero
Frank Ryan — Irish Republican Army fighter who led the Connolly Column
Elman Service — American anthropologist
Mehmet Shehu — future Albanian Communist Premier
Humphrey (Hugh) Slater — British painter
John Sommerfield — British author
George Sossenko — Russia-American writer
Žikica Jovanović Španac — Serb Yugoslav activist
Stephen Spender — British novelist
Sygmunt Stein — Yiddish-speaking journalist, former member of the Comintern and member of the Botwin battalion
Manfred Stern — General "Kléber" - 1936 commander of the first ("XI") Int. Brigade — called "Savior of Madrid" by the international press, then quietly replaced and his name later no longer mentioned.
Karol Świerczewski — Polish general
Gerda Taro — war photographer
Asim Vokshi — Albanian commander of the Garibaldi Battalion
Simone Weil — French philosopher
Tom Wintringham — British historian
Milton Wolff — last commander of the Abraham Lincoln Battalion
Wilhelm Zaisser — future East German secret police chief, 1936 commander of XIII International Brigade, 1937 the international forces in Spain
David Alfaro Siqueiros — Mexican muralist and member of the Mexican Communist Party
Mate Zalka — General "Lukacs" — 1936 commander XII International Brigade