The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Regions of the UK (4 members)
- Relation of production (1 member)
- Religion (7 members)
- Religions (5 members)
- Republic of Korea (1 member)
- Republics of the Soviet Union (8 members)
- Restaurant chains (1 member)
- Retired comrades (3 members)
- Revisionism (14 members)
- Revisionists (14 members)
- Revolution (1 member)
- Revolutionaries (26 members)
- Revolutionaries by nationality (4 members)
- Revolutionary Base Area (1 member)
- Revolutionary tactics (1 member)
- Revolutions (9 members)
- Right-wing ideologies (22 members)
- Right wing political parties (4 members)
- Rockefeller family (1 member)
- Rodney family of Delaware (1 member)
- Rulers of England (1 member)
- Russian Marxists (10 members)
- Russian agronomists (1 member)
- Russian state media (2 members)
- Russians (6 members)
- Russians by descent (3 members)
- Russians of Ukrainian descent (4 members)
- SACP comrades (0 members)
- STFU imperialist memes (2 members)
- STFU memes (1 member)
- Sarawak templates (1 member)
- Science (6 members)
- Scientists (3 members)
- Scribunto modules with errors (5 members)
- Search engines (1 member)
- Segregationists (1 member)
- Separatist states (6 members)
- Settler-colonial states (7 members)
- Settler colonialism (7 members)
- Settler colonialism (essays) (1 member)
- Sexism (2 members)
- Sign languages (1 member)
- Sino-Soviet split (1 member)
- Slave owners (5 members)
- Slavery (7 members)
- Slogans (11 members)
- Slogans in China (1 member)
- Slogans in the USSR (1 member)
- Slogans of the Communist Party of China (1 member)
- Slums (3 members)
- Social class (8 members)
- Social democracy (1 member)
- Social democratic parties (4 members)
- Social democrats (3 members)
- Social indicators (1 member)
- Social issues (10 members)
- Social media (7 members)
- Socialism (15 members)
- Socialism by country (11 members)
- Socialism in Albania (1 member)
- Socialism in Chile (1 member)
- Socialism in Germany (3 members)
- Socialism in India (2 members)
- Socialism in Ireland (1 member)
- Socialism in Japan (1 member)
- Socialism in Norway (1 member)
- Socialism in Poland (1 member)
- Socialism in the Netherlands (1 member)
- Socialism in the United States (7 members)
- Socialist Space Programs (1 member)
- Socialist art (2 members)
- Socialist intelligence agencies (4 members)
- Socialist leaders (2 members)
- Socialist media outlets (17 members)
- Socialist newspapers (22 members)
- Socialist podcasts (17 members)
- Socialist political parties (10 members)
- Socialist realism (3 members)
- Socialist rulers (8 members)
- Socialist states (7 members)
- Socialists (18 members)
- Socialists by nationality (3 members)
- Sociology (2 members)
- Software (4 members)
- Soldiers (2 members)
- Solzhenitsyn family (1 member)
- Song lyrics (28 members)
- South Korea (0 members)
- Soviet Union (4 members)
- Soviet Union navigational boxes (1 member)
- Soviet Union portal (3 members)
- Soviet agronomists (1 member)
- Soviet anti-USA posters (6 members)
- Soviet anti-fascist posters (1 member)
- Soviet military personnel of the Russian Civil War (1 member)
- Soviet military personnel of the Spanish Civil War (1 member)
- Soviet politicians (17 members)
- Soviet propaganda posters (37 members)
- Space Programs (1 member)
- Speeches (13 members)