This guy is The Mighty Penguin. Super strong, invulnerable, very mean. Better than explaining why he's called the penguin here is an exchange between him and a generic person who wonders the same thing:
Generic person: So, you call yourself the Mighty Penguin?
MP: Yes.
GP: Do you have penguin powers?
MP: No.
GP: ....did you somehow get your powers from a penguin?
MP: No.
GP: Are you similar to a penguin at all?
MP: Well...I can't fly.
GP: Ah I see...Then why do you call yourself The Mighty Penguin?
MP: I like penguins.
GP: Ah.
MP: They're cute.
GP: Yes, yes they are.
Anyway, I thought that would be funny and I thought it would also be funny if I made him extra mean. Nobody expects a guy called The Mighty Penguin to be very mean. Oh and I put the 'mighty' in front since DC probably holds the copyright to just 'The Penguin'.
Dc may hold the copyright to "the penguin" but I hold it for the word "the" your screwed now buddy I am sueing. If I remember correctly Bio holds the copyright for every vowel in the english language.