The power secret occult society known as the Circle of the Black Thorn was part of the 1999 - 2004 American TV series "Angel" a spin-off from the popular television series "Buffy the Vampire Slayer". Like Buffy, "Angel" was produced by Joss Whedon's production company, Mutant Enemy. This show involves the star Angel doing battle with evil demons or humans allied to them.

Members of the Circle of the Black Thorn were earthly instruments of the Senior Partners of the law film of Wolfram & Hart. They were charged with being the driving force behind Wolfram & Hart's apocalyptic plans and dedicated efforts to keep "man's inhumanity to man" perpetually spinning. The members of the Circle do not act because they are evil or believe in evil, but because being a Black Thorn allows them to amass power and wield that power with impunity. When all is said and done, demons and the Circle just can't overcome all of the ingenious efforts that are taken to save humanity. In the show, good always seems to beat evil with needed help from Angel.

More Info: en.wikipedia.org