Certainly it has to be a series of books, otherwise the villain could not continue.
From the comic books of my youth to modern series villains that always come back for more have been popular.
Holmes had his Moriarty, Spiderman has Doc Oc.
For me, the best is Ed McBain's Mort Orrechio, also known as Sanson, also known, inter alia, as the "deaf man". (Mort Orrechio = dead ear; Sanson = without sound).
McBain has used other aliases for the deaf man who has appeared in at least 4 and maybe 6 of the 87th Precinct police procedurals.
