The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Presidents of the United States (22 members)
- Professors (2 members)
- Progressives (2 members)
- ProleWiki Finances (3 members)
- ProleWiki Funding Required (1 member)
- ProleWiki administrators (2 members)
- ProleWiki comrades (6 members)
- ProleWiki news (essays) (2 members)
- ProleWiki official pages (12 members)
- ProleWiki policies and guidelines (1 member)
- ProleWiki technical contributor (1 member)
- Proletariat (3 members)
- Propaganda (9 members)
- Propaganda posters (17 members)
- Protest tactics (2 members)
- Protests (8 members)
- Province-level administrative divisions (4 members)
- Provinces of China (9 members)
- Proxy wars (1 member)
- Prussian Army personnel (1 member)
- Pseudo-intellectuals (2 members)
- Pseudoscience (3 members)
- Psychiatry (4 members)
- Publisher Organizations (2 members)
- Publishing companies (1 member)
- Puppet states (2 members)
- Quotes (15 members)
- Race (3 members)
- Racism (15 members)
- Racist propaganda (7 members)
- Racists (9 members)
- Rallies (1 member)
- Reactionaries (31 members)
- Reactionary slogans (1 member)
- Reading lists (9 members)
- Rebellions in the United States (1 member)
- Recipients of the Imperial Order of the Iron Crown (3rd Class) (1 member)
- Recipients of the Iron Cross (1939), 1st class (1 member)
- Recipients of the Iron Cross (1939), 2nd class (1 member)
- Recipients of the Knight's Cross of the Iron Cross (2 members)
- Recipients of the Knight's Cross of the Iron Cross with Oak Leaves (1 member)
- Recipients of the Knight's Cross of the Iron Cross with Oak Leaves, Swords, and Diamonds (1 member)
- Recipients of the Knight's Cross of the Iron Cross with Oak Leaves and Swords (1 member)
- Recipients of the Pour le Mérite (military class) (1 member)
- Recipients of the Silver Medal for Bravery (Austria), 1st class (1 member)
- Red Army officers (1 member)
- Red Army soldiers (6 members)
- Red Clarion article (1 member)
- Redirect pages (1 member)
- Redirects connected to a Wikibase item (4 members)
- Regions of the Russian Federation (1 member)
- 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)