My first encounter with The Master and Margarita came when I first saw this cover (can't recall where though).
That demon cat, as expected, dominates the majority of cover art for The Master and Margarita. Most covers use an illustration:
The cover art for the version I just bought is unique in that it's a photograph of a cat in profile against a rich russet sky (looks like red in the image, but trust me on the russet). Subdued, but still interesting.
Much classier than the cartoonish art for the newer Vintage release:
But this Penguin one is my favorite so far: