Just came back from The Wolf of Wall Street and I'm more convinced than ever that this idea really works... The actor I suggest actually eats a live fish in an act of aggression in the movie. He's comic relief in Wolf of Wall Street, but shows all the chops he needs to play Penguin as I describe him below.
So this one is going out on a limb, but I actually really like it.
The Penguin, as an extremely rich, young, only mildly deformed but extremely depraved, unmoral financial and/or tech company mogul, who very well may have murdered his parents as a young kid. Totally ruthless. Loves the finest things in life. Total rich kid scumbag. Smokes black blunts, and has high tech umbrellas (the type pictured here is actually by a company called Blunt). Impeccably dressed.
Comes from the same world as Bruce Wayne but obviously much younger... in many ways, a direct foil to Wayne. Whereas Bruce's parents were killed and it turned him into Batman, Cobblepot's first kill as Penguin was his parents and various kids who tormented him while growing up. He's a master of manipulation, tied to every person of power either through coercion, bribery, and carefully orchestrated murders. Rarely gets his own hands dirty, but when he does, he's absolutely vicious and sadistic.
Dresses in all black. Accent colors are a cool blue, and a sickly orange. Ice blue to symbolize his icy sociopathy and glacial patience in planning. Orange to reference the coloring of King Penguins, as well as to accent that the kid smokes WAY too much. Sallow eyes, short, fat, with a deformed right dominant hand that could have been fixed at birth if his parents hadn't been so totally apathetic, absent and neglectful.
And here's the ridiculous image of Joker & Penguin (a much sillier version that I did for the Joker thread) that inspired me to take Jonah Hill seriously as a really out-of-left field, thoroughly modern monster that merges a lot of the kinds of celebrity rich kid tech moguls that we see in the news & popular culture with the visual flare of a Bond villain.
And actually now that I've seen Wolf of Wall Street, I'm thoroughly convinced Leo would be a damn good Joker even though he's not at all my first pick for the role.