The Shadow Group was a terrorist organization that operated in the mid 24th century who were based on the planet Bajor. They were seemingly composed of Bajoran's who intended to commit actions in order to provoke a war between the United Federation of Planets and the Cardassian Union with the aim of bringing about the defeat of the latter of the two. This group consisted of former members of The Circle though unknown to many, the Shadow Group also consisted of former members of the Cardassian Obsidian Order who instead desired to cause incidents for the Federation. The organization was known to make use of Maquis starships in order to mask their operations.
At some point by 2372, this group was responsible for a targeted assassination against Tora Ziyal with a hate letter being directed at her. This prompted an investigation by Deep Space 9 personnel; including Kira Nerys, Odo and Garak. A second attempt failed when a member of the terrorist team committed suicide rather than be captured. Kira Nerys traced the pattern of the attackers to Bajor where she discovered the truth about the Shadow Group. Kira, Ziyal, Odo and Garak were later rescued by the USS Defiant and the incident saw the members of the Shadow Group being arrested for their crimes. (DS9 comic: "The Shadow Group")