The makeup job they did was very impressive. If you’d showed me a pic of Colin Farrell in character as Penguin and said “you have three months to guess the actor”, I wouldn’t be able.
I’d name about 7,400 others. Richard Kind? Danny DeVito? Jason Alexander? Joe Pesci? Every chunky, balding white guy I could think of! Hell, Burt Ward in a bit of stunt-casting/nudge-wink move?
Most makeup jobs you can still see/recognize the actor below (a bit of aging, a bit of weight gain or even stylized exaggerating for a fantasy/sci-fi type of project). But they went all-in on full transformation here. There is absolutely zero trace of Farrell remaining.
That’ll have to be nominated for - if not outright win - a boatload of awards when that time rolls around.
Throw in the voice on top of the makeup/visual and I would never guess that’s the actor underneath!