Secret societies

The Brethren of Purity (Arabic: اخوان‌الصفا‎‎ ikhwãn al-safã; also The Brethren of Sincerity) were a secret society of Muslim philosophers in Basra, Iraq, in the 8th or 10th century CE.

Tugendbund, or League of Virtue was a quasi-Masonic secret society founded in June 1808, in order to revive the national spirit of Prussians after their defeat of Napoleon.

The Free Officers (Arabic: حركة الضباط الأحرار‎‎ Ḥarakat aḍ-Ḍubbāṭ al-ʾAḥrār) were a group of nationalist officers in the armed forces of Egypt and Sudan that instigated the Egyptian Revolution of 1952.

A confraternity is generally a Christian voluntary association of lay people created for the purpose of promoting special works of Christian charity or piety, and approved by the Church hierarchy.

A secret society is a club or an organization whose activities, events, and inner functioning are concealed from non-members.

Leaderless resistance, or phantom cell structure, is a social resistance strategy in which small, independent groups (covert cells), including individuals (a solo cell called a "Lone Wolf"), challenge an established institution such as a law, economic system, social order, government, et cetera.

Satanism is a group of ideological and philosophical beliefs based on the character of Satan.

Organisation Consul (O.C.) was an ultra-nationalist force operating in Germany in 1921 and 1922.

Thuggee or tuggee (Hindi: Nepali ठग्गी ṭhaggī; Urdu: ٹھگ‎; Sanskrit: sthaga; Sindhi: ٺوڳي، ٺڳ‎; Kannada: ಠಕ್ಕ thakka) refers to the acts of Thugs, an organised gang of professional robbers and murderers.

The Sicarii (Modern Hebrew: סיקריים siqari'im) were a splinter group of the Jewish Zealots who, in the decades preceding Jerusalem's destruction in 70 CE, heavily opposed the Roman occupation of Judea and attempted to expel them and their sympathizers from the area.

The Vehmic courts, Vehmgericht, holy vehme, or simply Vehm, also spelt Feme, Vehmegericht, Fehmgericht, are names given to a "proto-vigilante" tribunal system of Westphalia in Germany active during the later Middle Ages, based on a fraternal organisation of lay judges called “free judges” (German: Freischöffen or French: francs-juges).

The Conspiracy of the Equals (French: Conjuration des Égaux) or Society of the Panthéon was a faction within the French Revolution led by François-Noël Babeuf.

Bulgarian Secret Central Revolutionary Committee (BSCRC) was a Bulgarian revolutionary organization founded in Plovdiv, then in Eastern Rumelia on February 10, 1885.

The Gadianton robbers (/ɡæd.iː.ˈæn.tʌn/), according to the Book of Mormon, were a secret criminal organization in ancient America.

A cabal is a group of people united in some close design together, usually to promote their private views or interests in an ideology, state, or other community, often by intrigue, usually unbeknown to persons outside their group.

The Germanenorden (Germanic or Teutonic Order, not to be confused with the medieval German order of the Teutonic Knights) was a völkisch secret society in early 20th-century Germany.