Who was Mark Twain's private secretary and later his biographer?

Mark Twain’s private secretary and later biographer was Albert Bigelow Paine. Paine became closely involved with Twain’s literary affairs and was given access to his papers before Twain’s death in 1910.

Paine’s major achievement was Mark Twain: A Biography, a four-volume work published from 1912 onward. He also edited Twain’s letters, speeches, notebooks, and portions of the autobiography, serving as a literary executor and editor of the estate.

Paine was not merely an office secretary or a contemporary newspaper colleague. He was an author in his own right, having begun his career in photography before turning to writing. His association with Twain lasted beyond Twain’s lifetime and made him one of the most influential early interpreters of Twain’s personal and literary history.

A common mix-up is confusing Paine with William Dean Howells, Twain’s famous author-friend and literary critic. Howells helped promote Twain’s work, but Paine was the secretary, biographer, and estate editor described here.