(But available to read in English!) I'll start us off with a few. Try to includes ones readers may not have heard of before.
  1. Hunger by Knut Hamsun
  2. Nada by Carmen Laforet
  3. The Master and Margarita by Mikhail Bulgakov
  4. Dialog of the Dogs by Cervantes
  5. Candide by Voltaire
  6. Wind Up Bird Chronicle by Haruki Murakami
    Suggested by @samanthastone
  7. Unformed Landscape by Peter Stamm
    Suggested by @kmr1391
  8. Like Water for Chocolate by Laura Esquivel
    Suggested by @bookishclaire
  9. The Stranger by Albert Camus
    Suggested by @vmacies
  10. Purge by Sofi Oksanen
    This is a phenomenal book about two women's experiences during/just after the Soviet occupation of Estonia. It's a dark & emotional read, but a great story about what it was/is like to be a woman in an occupied nation. Originally published in Finnish & based on a play of the same name (also by Oksanen).
    Suggested by @nelle
  11. Invitation to a Beheading by Vladimir Nabokov
    Lolita gets the most attention for a reason, but I think Invitation is better overall (at the very least it's just as thought-provoking and beautifully written/translated without being as nauseating). Originally written in Russian.
    Suggested by @nelle
  12. Invisible Cities - Italo Calvino
    Suggested by @victor
  13. The Shadow of The Wind by Carlos Ruiz Zafón
    Excellent book that I devoured because I found the descriptions so vivid and plot intriguing. Originally written in Spanish (La Sombra del Viento), I gave my brother the whole series in Spanish over the course of a few years and he really enjoyed it, too!
    Suggested by @e
  14. Momo by Michael Ende
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    His book (and subsequent movie) The Neverending Story gets all the glory but his previous book Momo is brilliant. An exploration of time, efficiency, and the effects on modern society, it's just as relevant now as it was when it was published in 1973. Maybe more so. Sadly the English translation version was out of print for years but McSweeney recently republished it in 2013 for its 40 year anniversary. Worth reading if you haven't.
    Suggested by @eatthelove
  15. The Dinner by Herman Koch
    Suggested by @RStrout
  16. The Elegance of the Hedgehog by Muriel Barbery
    Suggested by @RStrout
  17. A Dry White Season by André. P Brink
    Apartheid-era South Africa, follows a middle-class white man who begins to realise what his government is really doing.
    Suggested by @barefootmeds
  18. The Count of Monte Cristo
    Suggested by @saytrumbo
  19. The Reader by Bernhard Schlink
    Suggested by @sarahrberry