The group called the Dark Circle was first introduced in the pages of Adventure Comics #367, "No Escape From The Circle Of Death".
Original Continuity: New Earth
A mysterious group that first struck in the latter half of the 30th Century, the Dark Circle has attempted on several occasions to conquer Earth and the United Planets. Originally thought to be an alliance of five unknown worlds, the Dark Circle was ultimately revealed by the Legion of Super Heroes to be no more than 5 people - one from each of the different worlds belonging to the United Planets. The armies of the Dark Circle were composed of clones of the 5 ruling members.
5-Year Gap/Five Years Later
In the before the Zero Hour timeline whipped out this continuity the Dark Circle made an appearance. In an attempt to assassin the royal Queen Projectra while she slept the Dark Circle was setting up the remaining of the United Planets allies to desist from aiding Earth from the war with the Khunds.
The former Legionnaires and paramours Valor and Shadow Lass take down the Dark Circle cult within both Orando and the planet Cargg.
A version of the Dark Circle also appeared in the television series The Legion of Super-Heroes. The title of the episode was "In Your Dreams" and was directed by Brandon Vietti and the writing was done by Stan Berkowitz. It aired on March 22, 2008.
Ontir: A member of the planet Tsauron and double agent in the Science Police, later killed by Kimball Zendak.
Brainiac 4: Mother to the Legionnaire Brainiac 5 and one time leader of the dark Circle who killed the other leader of the organization.
Dev-Em: A Daxamite agent of the United Planets whos cloned body would make up a small but powerful army for the Dark Circle.
Tellus: Member of the Legion of Super-Heroes and infiltrated member.
Norak Kun: From the planet Naltor and somehow familiar with the Legionaire White Witch. Died from a self-inflicted Gorgath: A member of the Dark Circle from the planet N'cron
Goroth: A member of the species named the Fresish. He was a member for a time of the Dark Circle.