The funny thing is that Dublin criminals are often given nicknames like that by each other and the press, the most famous being The General aka Martin Cahill, who was played by Brendan Gleeson in John Boorman’s film of that name. In fact, another one is even called The Penguin https://www.google.co.uk/amp/s/www....rge-the-penquin-mitchell-pension-13515562.amp
Mobster nicknames were pretty common in the US back in the '30s and '40s -- Scarface, Legs, Pretty Boy, Fat Tony, The Nose, things like that. So the colorful nicknames for comic-book supervillains probably sounded less absurd in the Golden Age than they do in retrospect. (In the same way that superhero capes probably seemed less absurd because capes and cloaks were still relatively common fashion accessories.)