 If you liked
Black Cat
|
 ...then you might like
Noir
|
Both series involve ancient (Noir) or just very old (Black Cat) secret, influential organizations which somehow decide over the World's matters. I found similar that both series have at least one main character that has been related to these organizations starts living a different life but it is forced, one way or another, to cooperate with them.
Besides the similarities between the stories, I'll note that both were released in the earlies '00 and their OST is superb, setting a big difference with other shows.