Hard for me to picture any actor in that role, without some good makeup/prosthetics.
I would imagine Penguin to be a bit older than Batman.
I was just looking through photos and a vid of Penguin from the Arkham series (never played the game, but I like their take on him.)
Sorry Idk how to post photos, but the Arkham Penguin's facial features reminded me a little of actor Paul Ben-Victor (age 50).
He's been in a ton of movies, very recognizable face, I know him mainly as Spiros, the guy under The Greek in the second season of The Wire.
But I'd like to see them take a well known, completely unexpected actor, and through his portrayal, mannerisms, voice, costume, and makeup/prosthetics (maybe a fat suit, depending, or the actor gains a lot of weight) and completely transform them, like Carrel in Foxcatcher or Tom Cruise in Tropic Thunder.
Would love to see a good Penguin, not as the main bad guy, but in an important secondary role like Two Face in TDK. Be cool to see a lot of the Gotham Rogues Gallery in that capacity throughout the DCEU movies.