Trotskyism is the political ideology and branch of Marxism developed by Russian revolutionary and intellectual Leon Trotsky along with some other members of the Left Opposition and the Fourth International. Trotsky described himself as an orthodox Marxist, a revolutionary Marxist, and a Bolshevik–Leninist as well as a follower of Karl Marx, Frederick Engels, Vladimir Lenin, Karl Liebknecht, and Rosa Luxemburg. His relations with Lenin have been a source of intense historical debate. However, on balance, scholarly opinion among a range of prominent historians and political scientists such as E.H. Carr, Isaac Deutscher, Moshe Lewin, Ronald Suny, Richard B. Day and W. Bruce Lincoln was that Lenin’s desired “heir” would have been a collective responsibility in which Trotsky was placed in "an important role and within which Stalin would be dramatically demoted ".
The Fourth International (FI) was a political international established in France in 1938 by Leon Trotsky and his supporters, having been expelled from the Soviet Union and the Communist International.
The Trotskyist Fraction – Fourth International (TF-FI) is a political international of Trotskyist political organizations that claim to adhere to the political legacy of the Fourth International.
James Robertson (1928–2019) was the long-time and founding National Chairman of the Spartacist League (US), the original national section of the International Communist League. In his later years, Robertson was consultative member of the ICL's international executive committee.
Trotskyism in Vietnam was represented by those who, in left opposition to the Indochinese Communist Party (ICP) of Nguyen Ai Quoc, identified with the call by Leon Trotsky to re-found "vanguard parties of proletariat" on principles of "proletarian internationalism" and of "permanent revolution". Active in the 1930s in organising the Saigon waterfront, industry and transport, Trotskyists presented a significant challenge to the Moscow-aligned party in Cochinchina. Following the September 1945 Saigon uprising against the restoration of French colonial rule, Vietnamese Trotskyists were systematically hunted down and eliminated by both the French Sûreté and the Communist-front Viet Minh.
The Revolutionary Workers League is a small Trotskyist group formed in the United States in the late 1970s. The RWL still has about 20 active members.
The Spartacist League/U.S. is a Trotskyist political grouping which is the United States section of the International Communist League, formerly the International Spartacist Tendency. This Spartacist League named themselves after the original Spartacus League of Weimar Republic in Germany, but has no formal descent from it. The League self-identifies as a "revolutionary communist" organization.
The International Socialist Group (ISG) was a Trotskyist organisation in Britain. It was the British section of the Fourth International (FI) until 2009 when it dissolved into Socialist Resistance.
The International Committee of the Fourth International (ICFI) is a public faction of the Fourth International founded in 1953. Today two Trotskyist internationals claim to be the continuations of the ICFI; one with sections named Socialist Equality Party which publishes the World Socialist Web Site, and another linked to the Workers Revolutionary Party in the UK.
The International Marxist Group (IMG) was a Trotskyist group in Britain between 1968 and 1982. It was the British Section of the Fourth International. It had around 1,000 members and supporters in the late 1970s. In 1980, it had 682 members; by 1982, when it changed its name to the Socialist League, membership had fallen to 534.
The International Communist League (Fourth Internationalist) abbreviated as ICL(FI), earlier known as the international Spartacist tendency (iSt) is a Trotskyist international. Its largest constituent party is the Spartacist League (US). There are smaller sections of the ICL (FI) in Mexico, Canada, France, Germany, Ireland, Italy, Japan, South Africa, Australia, Greece and the United Kingdom.
The phrase Fifth International refers to the efforts made by groups of socialists and communists to create a new workers' international.
Orthodox Trotskyism is a branch of Trotskyism which aims to adhere more closely to the philosophy, methods and positions of Leon Trotsky and the early Fourth International, Vladimir Lenin and Karl Marx than other avowed Trotskyists.
Anticapitalistas, known as Izquierda Anticapitalista until January 2015 and as Espacio Alternativo from 1995 to November 2008, is a socialist political organisation that works as a confederation in Spain. Anticapitalistas is defined as a revolutionary socialism, anti-capitalist, proletarian internationalist, republican, and eco-socialist organisation, assuming Marxism in an open, plural, and critical sense. Its stated objective is the rebuilding of the revolutionary project through the creation of a unitary, anti-capitalist political expression sustained by the anti-globalisation movement, the labor movement, and the social movements at large. It is a member of the Fourth International (post-reunification), a Trotskyist international organisation reformed in 1963.
Far-left politics in the United Kingdom have existed since at least the 1840s, with the formation of various organisations following ideologies such as Marxism, revolutionary socialism, communism, anarchism and syndicalism.
The International Bolshevik Tendency is an international Trotskyist organisation.
Algeria – Socialist Workers Party, Workers' Party 
Argentina – Movement for Socialism, Self-determination and Freedom, Socialist Left, Socialist Workers' Party, United Socialist Workers' Party, Workers' Party, Workers' Socialist Movement 
Australia – Socialist Alternative, Socialist Equality Party, Solidarity, Spartacist League, [1] Workers' Liberty Australia, Freedom Socialist Party 
Austria – Left Turn, Socialist Left Party, The Spark, Workers Viewpoint 
Azerbaijan – HAQİQAT
Bangladesh – Communist Party of Bangladesh (Marxist–Leninist) (Section of the Fourth International)
Belgium - International Workers' League, Left Socialist Party, Anticapitalist Left 
Bolivia – Revolutionary Worker League – Fourth International, Revolutionary Workers Party, Workers' Socialist Movement 
Botswana – International Socialist Organization 
Brazil – Freedom, Socialism and Revolution, Revolts, Revolutionary Workers' Movement, Socialist Democracy, Socialist Workers' Current, United Socialist Workers' Party, Workers' Cause Party 
Canada – International Socialists, Socialist Action, Socialist Alternative, Revolutionary Communist Party, Trotskyist League in Quebec [2] and Canada [3] 
China – China Worker [4] 
Chile – Revolutionary Workers Party, Movimiento Anticapitalista, [5] 
Colombia – Presents for Socialism 
Costa Rica – New Socialist Party, Socialist Organization, Workers' Party 
Cyprus – New Internationalist Left, Workers' Democracy 
Czech Republic – Marxist Alternative, Socialist Alternative Future, Socialist Organisation of Working People, Socialist Solidarity,
Denmark – International Socialists, Socialist Workers Party, Revolutionary Socialists (IMT) 
Egypt – Revolutionary Socialists 
Finland – Marxist Workers' League, Socialist Alternative 
France – Révolution Permanente, Independent Workers' Party, New Anticapitalist Party, Revolutionary Left, Trotskyist League of France, Workers' Struggle 
Germany – The Spark, Revolutionary Internationalist Organisation, Socialist Equality Party, Socialist Alternative, Socialist Organisation 'Solidarity', Workers' Power, Spartakist-Arbeiterpartei [6] 
Ghana – International Socialist Organisation 
Greece – Internationalist Workers' Left, Organisation of Internationalist Communists of Greece, Organization of Communist Internationalists of Greece–Spartacus, Socialist Workers' Party, Start – Socialist Internationalist Organisation, Trotskyist Group of Greece, [7] Workers Revolutionary Party 
India – Radical Socialist, [8] New Socialist Alternative, Workers' Socialist Party
Indonesia - Perhimpunan Sosialis Revolusioner, [9] Angkatan Bolshevik Revolusioner Internasionalis (ABRI) [10] 
Iran – Socialist Workers' Party of Iran 
Ireland – People Before Profit, Solidarity, Socialist Party, Socialist Workers Network, Militant Left 
Israel and 
Palestine – Socialist Struggle Movement 
Italy – Left Classe Revolution, [11] Workers' Communist Party, Communist Alternative Party, Anticapitalist Left 
Ivory Coast – Militant Côte d'Ivoire
Japan – Japan Revolutionary Communist League, Spartacist Group Japan, [12] Japan Revolutionary Communist League (Revolutionary Marxist Faction) 
South Korea – Workers' Solidarity, Bolshevik Group, [13] March To Socialism [14] 
Lebanon – Revolutionary Communist Group 
Malaysia - Socialist Alternative 
Mexico – Socialist Workers Movement 
Netherlands – Socialist Alternative Politics, Socialist Alternative, International Socialists, Vonk (Revolutionary Communist International)
New Zealand – International Socialist Organisation, Socialist Voice, Socialist Aotearoa 
Nicaragua – Workers' Revolutionary Party 
Nigeria – Democratic Socialist Movement, Movement for a Socialist Alternative 
Norway – Internationalist League of Norway 
Pakistan – Socialist Movement Pakistan, The Struggle Pakistan 
Paraguay – Workers' Party 
Peru – Workers' Revolutionary Party, Socialist Workers Party, Socialist Workers Party (1992)
Poland – Socialist Alternative, Workers' Democracy 
Portugal – Revolutionary Socialism, Socialist Alternative Movement 
Romania – Hand of Labour [15] 
Russia – Organisation of Communist Internationalists, Revolutionary Workers' Party, Russian Socialist Movement, Socialist Alternative, Socialist Tendency
South Africa – Spartacist South Africa, [16] Workers and Socialist Party, Workers International Vanguard Party, Keep Left, African Peoples' Democratic Union of Southern Africa, International Socialist Movement, Non-European Unity Movement 
Spain – Revolutionary Workers' Party, Internationalist Struggle, Red Current, Workers' Revolutionary Current, Revolutionary Left, Revolutionary Socialism, Anticapitalistas, Internationalist Socialist Workers' Party, Revolutionary Anticapitalist Left 
Sri Lanka – Lanka Equal Society Party, Lanka Equal Society Party (Alternative Group), New Equal Society Party, United Socialist Party, Socialist Party of Sri Lanka, Socialist Equality Party, Revolutionary Workers Party 
Sudan – Socialist Alternative
Sweden – Socialist Party, Socialist Alternative, International Socialists, Workers' Power 
Switzerland – Solidarity, The Spark
Taiwan - International Socialist Forward, The Spark(IMT Taiwan)
Thailand – Socialist Workers Thailand
Togo – Workers' Party 
Tunisia – Socialist Alternative, Workers' Left League 
Turkey – Revolutionary Workers' Party, Revolutionary Socialist Workers' Party, New Way, Socialist Alternative, Workers' Fraternity Party 
Ukraine – Commune, [17] Social Movement, Ukrainian Socialist League
United Kingdom – Alliance for Workers' Liberty, Communist League, International Socialist League, Workers' Power, Socialist Action, Socialist Appeal, Socialist Equality Party, Socialist Resistance, Socialist Workers' Party, Spartacist League, Workers' Fight, Workers International to Rebuild the Fourth International, Workers Revolutionary Party, Socialist Alternative, Revolutionary Communist Party 
United States – Revolutionary Communists of America [18] (RCI), Socialist Alternative, Socialist Action, Socialist Equality Party, Freedom Socialist Party, Fourth International Caucus, Internationalist Group, Refoundation and Revolution, Spartacist League, Socialist Workers Organization, Socialist Organizer, The Left Party US, Left Voice, [19] Spark, Revolutionary Workers League, Workers' Voice
Uruguay – Workers' Party, International Socialism; Revolutionary Workers' Party, Fourth International Posadist, Current of Workers for Socialism
Venezuela – Revolutionary Socialism, Revolutionary Marxist Current, League of Workers for Socialism
Zimbabwe – International Socialist Organisation
