World Lit

Poland: Kochanowski, Mickiewicz, Sienkiewicz, Gombrowicz, Miłosz

England:Beowulf, Chaucer, Shakespeare, Milton

Italy: Divine Comedy, Decameron, L'orlando Furioso, Zeno's Conscience, Invisible Cities.

Spain:
Mio Cid, Don Quijote, ???

China:
Confucius, Laozi, Sima Qian, Li Bo/Du Fu, And some of the 'chinese classic books' (Outlaws of the marsh, Journey, RoTK, etc)

Japan:
Kojiki, Tale of Genji, Basho, Kokoro, Akutagawa, etc

Russia: Pushkin, Gogol, (Dostoevsky), Tolstoy, Solzhenitsyn, (Turgenev or Chekhov), bulgakov

Brazil:
José de Alencar,Lima Barreto,Machado de Assis, João Guimarães Rosa, Graciliano Ramos, Jorge Amado;

S.Africa:
South Africa: The Story of an African Farm, July's People, Disgrace, Cry, the Beloved Country, Triomf

France:
Les Confessions, Madame Bovary, Les Fleurs du Mal, Matter and memory, À la recherche du temps perdu

Valéry, Giono, La Fontaine, de Nerval, Molière

Wales:
Y Mabinogion, Iolo Morgannwg, Kate Roberts, Dylan Thomas (for the Anglos), Beirdd y Tywysogion.

Czechoslovakia/Czech Republic:
Bohumil Hrabal, Jaroslav Hasek, Karel Capek, Ladislav Klima, Jiri Weil

Germany:
Georg Büchner, Stefan George, Georg Trakl, Robert Musil, Albrecht Döblin, Bertolt Brecht

Grass is not worth the list, Hesse arguably neither. Latter is also swiss, if you really consider the nationality and not the language! Hölderlin deserves to be on such a list, though, especially because he is genuinely german with his... quixotic (? I google translated this), youthful manner.

Norway... After the 400 years of oppressive darkness and being a cultural backwater: Various old poems written down in the icelandic sagas, Ludvig Holberg and Henrik Wergeland, the former often called father of modern Danish literature, the latter known as the father of new norwegian literature. Peter Asbjornsen and Jorgen Moe, gatherers of folk tales from all around norway. Knut Hamsun, probably a bit more known here on /lit/, providing me with personal favourites such as Mysteries, The Growth of the Soil, The Wild Choir, Under the Autumn Star, and many more. Tarjei Vesaas, another mighty author; The Birds, The Ice Palace, Spring Night. Female author Sigrid Undset also wrote a classic series set in medival times called Kristin Lavransdatter. And of course famous playwright Henrik Ibsen. Alexander Kiellan also worth mentioning.

Some significant modern authors include Lars Saabye Christensen, his most famous tite is "Beatles", Tom Egeland, writer of rather known title "Relic". Aaaand that's all I'm bothering to write down now.

Portugal:
Fernando Pessoa, José Saramago, Eça de Queirós, José Gomes Ferreira, Luis de Camões.
Os Maias, Os Lusíadas, Levantado do Chão, Livro do Desassossego, As Aventuras de João sem Medo.
Notable mentions: Até Amanhã Camaradas by Manuel Tiago (The pseudonym of Communist Party leader Álvaro Cunhal),
Os Esteiros by Soeiro Pereira Gomes,
Um Deus Passeando pela Brisa da Tarde by Mário de Carvalho

Argentina:
Sabato, Borges, Casares, Mujica Lainez, Cortazar.

El Salvador
Salvador Salazar Arrue, Alvaro Menendez Leal, Roque Dalton García.