Arthur C. Clarke: The Authorised Biography (Neil McAleer) Good source on Clarke's life and times by another sci-fi writer
Who is Ayn Rand? (Barbara and Nathaniel Branden) is the only "authorised" biography of Rand during her lifetime
The Life of Graham Greene was by English professor Norman Sherry. Two volumes are out, the third is caught in a row.
R.K. Narayan, The Early Years, 1906-1945 (Susan Ram and N. Ram) a slightly academic fact file of those years