I think St Peter may sometimes be referred to as 'The Enforcer'. Here's one reference:
http://rhy-himself.de...the-Enforcer-58972828
I'm just guessing but this may be for his leadership role among the disciples or because he acts as 'bouncer' at the pearly gates.
Part of his Wikipedia entry says:
Over the years "St. Peter" has evolved into a stock character that is now widely used in jokes, cartoons, comedies, dramas, and plays. Such caricatures almost all play upon Peter's role as the "keeper of the keys of the kingdom of heaven" in Matthew 16:19, on the basis of which he is often depicted as an elderly, bearded man who sits at the pearly gates that serve as heaven's main entrance, often portrayed as a sort of hotel-style doorman / bouncer who personally interviews prospective entrants into Heaven, often seated behind a desk, or standing at a lectern. He usually has a big book in which the names of the saved are written.