Bulgakov -- what a joy, and this one is a favorite. 20 or so years ago Harvey Pekar's review of "The Master and Margarita" in the Chicago Tribune book section, edited by Larry Kart, was what introduced me to Bulgakov.
I learned about Bulgakov and A Dog's Heart from a footnote in Orlando Figes's A People's Tragedy: The Russian Revolution 1891-1924. I've since read both that book and The Master and Margaritain their Penguin Classics translations.
Now reading:
Alaistar Reynolds - Blue Remembered Earth (2012, Gollancz)