My favourite was Ken Franklin, played by Jack Cassidy in Murder by the Book. Cassidy was particularly good at playing smarmy villains. With regard to the Clive Revill episode, the problem I had with it was that Joe Devlin was supposed to be from Belfast in Northern Ireland but played the part using the type of southern Irish accent only found in tv programmes. I can only assume it was thought that an American audience would not recognise or identify with a Northern Irish accent.
I wish I can remember his name, and the episode. He was a charming Irishman whom Columbo acknowledges that he genuinely likes. Columbo seems regretful that this guy truly is the murderer. <br />
If you're a Columbo buff, perhaps you remember.
Joe Devlin! Yes that's the one. Thanks!