I know these are well known classics, but they are still favorites of mine.
One of my favorite Bat & Cat moments by the late Don Newton:
A lovely Catwoman by Jose Luis Garcia-Lopez
Speaking of Garcia-Lopez, he and Dick Giordano had an elegance in their work on Bat-related (and other DC-) characters , both individually and as a team on this cover:
and here's his Joker:
And speaking of the clown prince of crime, I've always considered this the definitive Joker panel, by Marshall Rogers:
And the definitive Batman, rivaled only by Garcia-Lopez and Giordano. Neal Adams:
And a couple of panels by Dick Giordano From There is no hope in Crime Alley, my all time favorite Batman short story:
The definitive Two-face, Adams again: