Non-Debatable: 16 TV Characters Who'd Dominate As A Moderator

Downton Abbey - The Dowager Countess of Grantham
This woman is formidable enough that all she has to do is look down her nose at the candidate and they'd be stumbling over their words attempting to backpedal on their stretched truths and flat-out lies. We're actually not sure it's physically possible to lie to her - you would be turned to dust by a haughty stare of disbelief.  The confessions alone would be worth tuning in for.