My own personal favourite authors, in no particular order! Some of these I love for one particular masterpiece, some for the whole corpus of their work... You may notice that I don't distinguish between 'fact' and 'fiction'; indeed, I believe that it is the overriding concern of these great authors with personal and universal truths which allows their work to transcend such classification.
The reason that I have left out such giants of English literature as T.S. Eliot and W.H.Auden or such international superstars as Goethe or Dante is not because I don't rate their books highly, but because they have not been so personally inspiring for me in my life. Maybe they intrigued me or fascinated me intellectually, but they did not move me or enlighten me as did the examples below!

Jane Austen
William Shakespeare
Redmond O'Hanlon
Peter Matthiessen
Florinda Donner
Taisha Abelar
Don Miguel Ruiz
Alan Watts
Osho
Heathcote Williams
Jalaluddin Rumi
Carlos Castaneda
Kahlil Gibran
Shepherd Hoodwin
Mary Webb
Leo Tolstoy
Fyodor Dostoevsky
Louise Erdrich
Lyall Watson
Barbara Kingsolver
R.K. Narayan
Graham Greene
Laurens van der Post
Hugh Brody
William Wordsworth
John Keats