The Thorn Circle was a conspiracy aligned with the Dark Convention in the mid-1990's. At the center of the group was Abraham Thorn, along with Ben Journey.
In 1995, the Thorn Circle attempted and failed to assassinate Governor-General Elias Hucksteen; most of the members of the group were caught, and those who eluded capture went into hiding.
In March of 1996, Thorn made his youngest daughter the Secret Keeper for the group.
In June of 2009, the Thorn Circle returned to activity when Thorn orchestrated the crash of the Roanoke Underhill by closing off the train's entryway into the Lands Below.
In the Spring of 2010, the Thorn Circle launched attacks against both the Gringotts branch in the Atlanta Goblin Market and the New Amsterdam Academy for Witches and Wizards, causing the collapse of both buildings.
In June of 2010, Alexandra Quick learned from Absalom Thorn that the Thorn Circle's primary objection to the American Wizarding Confederation were the practices of the Deathly Regiment.