The Master and Margarita by Mikhail Bulgakov
Bulgakov swings gracefully between the theatrical, the vulgar, the cartoonish, the caustically satiric, and even at times the profound and the sublime. I don't know how much of the satire I missed due to my relative unfamiliarity with the Soviet Union in the 1920s, though his attacks on the groveling and conforming literary establishment of the time are quite clear and wonderfully handled. I especially loved his satires of hustling for real estate. Behemoth the Tomcat is an indelible character - even if his supporting role in the book is smaller than you might imagine given his prominence on the covers of many editions of this book.
But the most thought provoking element of the book may be the novel-within-the-novel about Pontius Pilate. It functions simultaneously as a deep rupture from the main narrative, yet Bulgakov also successfully integrates it in myriad ways. Techniques associated with postmodernism stretch as far back as Cervantes, but this novel fascinates in how it feels both of its time and startlingly contemporary.
But most important of all, it's damn funny.