Well, there's also (most appositely) the familiar of the court:

(n.) A confidential officer employed in the service of the tribunal, especially in apprehending and imprisoning the accused. (Onelook)

But it's an interesting little family of words, growing by a process of transfer from its Latin roots... now, hang on, was ASp practising her irony, or was she just playing the familiar role of Devil's Advocate? ;)