List of foreign volunteers
Twenty-four Filipinos served in the French Army during World War I.
Some Americans served in the Philippine National Guard.
Filipinos fought on both sides of the Spanish Civil War.
During the Pacific War, Filipinos served in various pro-Japanese militias:
The Bisigbakal ñg Tagala (Tagalog "Iron Arm of Tagala") was formed in January 1945 to assist the Japanese in maintaining peace and order   in Manila.  The Bisig Bakal received weapons, uniforms, and training from the Japanese.
About five thousand Filipinos served in a militia called the Makapili, which was under Japanese command. The unit was formed on 10 November 1944 and was issued around two thousand rifles by the Japanese.  Its headquarters was located at the Christ the King compound in Quezon City.  The organization was active in the Manila area, and in the nearby provinces of Rizal, Laguna, Bulacan, and Nueva Ecija.  This militia made its last stand at Marikina in 1945.  Other militias similar to the Makapili were:  the Borong-Borong Gang, Kaigun Hatai, and Nishimura Butai.
The Pambansang Pag-asa ng mga Anak ni Rizal (Tagalog "National Hope of the Children of Rizal") consisted of Ganáps in Pililla, Rizal, who were organized into a semi-military unit with the assistance of the Japanese.  Also known as Pampar, they wore blue denim uniforms with short pants and were drilled along Japanese military lines.  They performed sentry duties for the Japanese, and functioned as auxiliary troops of the Japanese army.  They independently conducted raids against guerrilla camps.
The Yoin, incorrectly known as U.N. or United Nippon, were members of the Japanese Auxiliary Army drawn from the ranks of the Ganáp Party.  They were trained for military purposes and wore Japanese regular uniforms.  They were used as replacements in the ranks of Japanese infantry.  Their counterparts in the Japanese Empire were the Koreans, Formosans, and Manchuokuans pressed into the Japanese army.
Some Americans and some Japanese fought with Filipino guerrillas.
One American joined the Huks.
One Italian pilot participated in the overthrow of the Marcos administration.
Filipinos, recruited by the Moro Islamic Liberation Front, fought in the Soviet–Afghan War.  (See Abdurajak Abubakar Janjalani)
One German ex-paratrooper participated in the 1989 coup
Filipinos hired by private military companies worked in Afghanistan and Iraq.
Filipinos fought in the Syrian Civil War.
Forty foreign fighters, from Indonesia, Malaysia, Yemen, and Chechnya, fought in the Siege of Marawi.

Finnish: As part of the Jäger Movement, a Finnish battalion was formed and served under the German Empire against the Russian Empire.
1,408 Finns volunteered to serve in the 5th SS Panzer Division Wiking, against the USSR.

French: Foreign Legion - A wing of the French Army which recruits foreign nationals.
9,000 French fought in the International Brigades during the Spanish Civil War in the side of the Republicans. some also fought for the Nationalists
Some French emigres who fled to Britain fought in the British Army of the Napoleonic Wars.
Charlemagne Regiment of the SS fought for Germany in the Second World War.
Chasseurs Britanniques of the Napoleonic Wars.
Legion of French Volunteers Against Bolshevism a collaborationist force of French who fought Soviet partisans for Nazi Germany.
From 1991 to 1994, during the Croatian War of Independence and the Bosnian War, a number of French volunteers fought alongside the Croats in the King Tomislav Brigade.
7 Independent Company (Rhodesia).

German: Landsknecht
Hessian (soldier)
King's German Legion in the Napoleonic Wars.
During the American Civil War Germany was the place of birth for thousands of Union soldiers. Several German speaking regiments existed such as the 9th Ohio Infantry, or the 74th Pennsylvania Infantry.
In the Spanish Civil War, the state-sponsored Condor Legion fought for the Nationalists, while the Thaelmann Battalion fought for the Republicans.
From 1991 to 1994, during the Croatian War of Independence and the Bosnian War, a number of former Bundeswehr and East-German army members fought alongside the Croats in the King Tomislav Brigade. The brigade's executive officer at the time of the outbreak of the Bosnian Croat War was former Bundeswehr officer Jürgen Schmidt, who died while leading his troops against Bosnian Muslim forces near Gornji Vakuf, in January 1993. In another action, a German-volunteer patrol, led by former Bundeswehr member Michael Homeister, ambushed and killed two Serbs manning an observation post.

Greek: The Greek Battalion of Balaklava participated in the Russo-Turkish wars of 1768–1774, 1787–1792 and 1806–1812 on the side of the Russian Empire.
The Greek Volunteer Guard, fought in the Bosnian War on the side of the Army of Republika Srpska.
The Greek Volunteer Legion, fought in the Crimean War on the side of the Russian Empire.

Indian: The Free Indian Legion was a volunteer legion made up of Indian POWs. The legion was first part of the Wehrmacht but transferred to the Waffen-SS late in the war.
Battaglione Azad Hindoustan.

Irish: See also Irish military diaspora.

The Irish Brigade in the French Army from 1690 and through the eighteenth century.
The Irish Legion fought for Imperial France during the Napoleonic Wars
1st Regiment Venezuelan Rifles – Irish regiment that was part of the British Legions fighting in the South American Wars of Independence took part in the Venezuelan War of Independence.
St. Patrick's Battalion in the Mexican Army during the Mexican–American War.
The Irish Brigade which served on the Union side in the American Civil War in the 1860s
Irish commandos in the Boer Army during the Boer War
Connolly Column, fought for the Spanish republic in the Spanish Civil War.
The Irish Brigade which fought for the Nationalist rebels in the Spanish Civil War
Irish Papal Battalion fought for the Papal States prior to Italian Unification.
Irish Regiment of Canada fought in WW1 and WW2 for Canada along with the Irish Fusillers (Canadian).
South African Irish Regiment fought for the Union of South Africa both in WW1 and WW2 and was later transformed to a reserve unit which still forms part of the modern Republic of South African Army.

Israeli: Mahal – Program for non-Israelis between the age of 18–24 to serve in the IDF.

Italian: The Redshirts of Giuseppe Garibaldi fought in Southern Italy and Uruguay.
Corpo Truppe Volontarie in the Spanish Civil War.
Division Garibaldi fought under Josip Broz Tito's command as a part of NOVJ in Dalmatia and Bosnia, during the Second World War

Japanese: Kempeitai Auxiliary units included colonial subjects such as Formosans, Indochinese, Koreans, and Malays.  Foreigners included Chinese, Filipinos and Manchuokuans.
Former Japanese soldiers fought alongside anti-colonial guerrillas in the First Indochina War, Indonesian National Revolution, and the Malayan Emergency. They also fought on both sides of the Chinese Civil War.

Korean: Korean Augmentation to the United States Army

Moroccan: Fuerzas Regulares Indígenas in the 1934 Asturian uprising and the Spanish Civil War.

Nepalese: Gurkhas in the British Army.
Gorkhas in the Indian Army.
Gurkha Contingent in the Singapore Police Force
Gurkha Reserve Unit – a similar type force in Brunei.
Foreign Legion in the French Army.

Polish: Brigades in the Spanish Civil War.
Polish Lancers and other Polish forces in the Army of Napoleon.
Polish Volunteers in many wars and revolutions of the 19th century, including Spring of Nations, Crimean War (on Turkish side) and The Paris Commune.
The Blue Army, fought on the western front for the Allies during WW1.
The Polish Legions, which fought for the Central Powers.
Polish Volunteers served in the RAF during WW2.

Portuguese: Legião Viriato in the Spanish Civil War.

Rhodesian: There were hundreds of foreign volunteers in the Rhodesian Security Forces during the Rhodesian Bush War. The Rhodesian Army accepted foreign volunteers, almost all of whom were required to speak English, as they were integrated into regular units (usually the Rhodesian Light Infantry) alongside locally based soldiers. The exception was 7 Independent Company, a short-lived unit made up entirely of French-speaking personnel, led by francophone officers, which existed between 1977 and 1978.

Russian: The Armed Forces of the Russian Federation have since 2010 or so begun to recruit CIS volunteers. See Armed Forces of the Russian Federation#Personnel.
A number of Russian soldiers would fight for Ukraine during the Russo-Ukrainian War as part of the Freedom of Russia Legion.
Soviet Volunteer Group, between 1937-1941 as part of the Republic of China Air Force during the Second Sino-Japanese War.
Some Russians fought for the Allies on the Western Front of WW1 as part of the Russian Legion. They were former members of the Russian Expeditionary Force.