If the question is "which actor/actress do you have the most of", it doesn't say "Horror" or exclude TV then it would have to be:
Bud Osborne, Stanley Andrews, Tom London, Edmund Cobb, Robert Fraser, Kenne Duncan, Lane Chandler, George Chesebro (his name seems to be in every cast list, but I still can't figure out which one he is!), Charles King, I. Stanford Jolley, Yakima Canutt, Dave O'Brien, Moe Howard, Larry Fine, Eddie Parker, etc.

I can't think of an actress with the credits these men have. Minerva? Sarah Padden, Mary Gordon, Ellen Corby, Sara Allgood, Larry Mondello's Mother, etc.

Horror? I think Karloff has more extant films (especially when you count his TV work..if you bought THRILLER, for example, there's 67 appearances alone) than Lugosi. I am sure I have everything that you can have on those two. 
But it could be Carradine with more fim titles. He was probably in more films and TV than Karloff, but I don't have all those dozens of things he did in his last 20 years or so.  He better watch out, though, Conrad Brooks might catch him!

Last Edited By: MYST0 Oct 11 11 1:18 AM. Edited 1 times.