Sullivan and Cromwell
An eternal succubus, famously thrown out of heaven with Beelzebub in Milton’s Paradise Lost. Its partners are immortal, cannot tolerate sunlinght and have an age-old, iron grip on frozen heart of the legal department of Goldman Sachs.
To be safe, a well-prepared visitor to 125 Broad Street should take holy water, garlic, crucifixes and ideally Gregory Peck (but failing him, Tubular Bells on the Walkman).
Important disclaimer: Sullivan and Cromwell is actually a celebrated Manhattan firm of US Attorneys. It isn't really a disguised coven of vampires. As far as I know.