Henrik Ibsen
August Strindberg
Verner von Heidenstam/Selma Lagerlöf - Heidenstam is better but too local, so they can share
Knut Hamsun
Karen Blixen
Gunnar Ekelöf
Halldór Laxness
Väinö Linna
William Heinesen
Tove Jansson
Frank Wedekind
Rainer Maria Rilke
Robert Musil
Thomas Mann
Bertolt Brecht
Ernst Jünger
Paul Celan
Heiner Müller
Günter Grass
Thomas Bernhard
Max Frisch
Christa Wolf
W. G. Sebald
Elfriede Jelinek
Durs Grünbein
Thank you so much for your lists, they're much appreciated. I really don't know enough about the German/Nordic/English languages/literatures to even begin to compile those lists.
My only regret is that there were not enough spots for German writers for you to include the great Anne Seghers. And there is just one little disagreement we have; I'm a great fan of the East German poet Peter Huchel, so I'd prefer him to Durs Grünbein to represent East German poetry, but I'm clearly on the side of the minority here, since even Wikipedia claims 'Grünbein is hailed as the most significant and successful poet to emerge from the former East Germany.'
On the other hand, congratulations on passing Hellas' Male-Judge-Blindness rule. A greatly admired childhood friend of mine, feminist, painter, poet and the person who introduced me to Eastern Thought, once explained to me that whoever puts together a list of great/favorite writers from the 20th. Century and does not include at least 20% female writers suffers from Male-Blindness on his judgment. You included 5 out of 25 female writers in your list (Selma, Karen, Tove, Christa and Mrs. Jelinek).
Of course, for the French and Portuguese languages, being literatures that I know well enough, I came up with a similar distribution of 5 out of 25 writers being female (Sophia, Clarice, Adelia, Margarite and Nathalie).
On the other hand, my ignorance concerning Spanish and Italian language literatures shows up, not only on the many unintentional oversights I had (as opposed to the French side where I intentionally left out Apollinaire, Gracq, Genet, Michaux, Tournier, Maalouf, Quignard and Bonnefoy); my ignorance shows up above all in the fact that I could not come up with ONE female writer to include on those lists, I'm ashamed to say.
Lastly, I'd like to send a shout-out to American and British fellow WLF members: come on, list the great 20th. Century writers from your language (I can only think of ten: Henry James, Kipling, Faulkner, Wodehouse, Auden, Larkin, Coover, Dillard and Ozick).