The Dark Convention is a group of wizards in North America who are, depending on one's source of information, an evil cabal of warlocks intent on destroying civilization, or a group of men who feel disenfranchised by not being in charge and want to take power away from the men who are in charge. The librarian of the Charmbridge Academy, Mrs. Minder, claims that the Convention are "a bunch of bitter old cranks boiling death-draughts in their cellars."
Ben Journey explained to Alexandra Quick that the Covention consisted primarily of wizards who opposed the Governor-General, and that American paranoia inspired by Voldemort's takeover in Britain led to the interrogation and imprisonment of many wizards who voiced disagreement with official policy (similar in some ways to McCarthyism and the Red Scare). He further made the delicate distinction that "'Dark' is a word most of the wizarding community uses to mean 'magic we don't approve of'."
In the mid-1990's, a conspiracy known as the "Thorn Circle," led by Abraham Everard Thorn, attempted to seize power from the Confederation of Wizards. After an unsuccessful assassination attempt against Governor-General Elias Hucksteen, most conspirators were imprisoned or killed, and those who escaped arrest went into hiding.
According to Maximilian King, the Dark Convention uses gatherings of young would-be Dark Arts practitioners, such as the Mors Mortis Society, to recruit new members. Thorn later explained that "most members of the Dark Convention are outcasts with no particular ambitions," but that "some have terrible ambitions, and many, ambitious or not, are simply twisted and perverse." He further clarified that his Circle of followers was not part of the Dark Convention, but rather allied with it in their shared "hatred of the Confederation."