American evangelist and reformer, a major public speaker and writer in the Holiness movement of the late 19th century.

Hannah Whitall grew up in a strict Quaker home and had from childhood a deep concern with religion and a habit of introspection. In 1851 she married Robert P. Smith, also a Quaker, and in 1865 they moved to Millville, New Jersey, where they came under the influence of the Wesleyan-based Holiness movement, a revivalistic creed based on sanctification by faith and the direct experience of salvation. Robert Smith soon began preaching at Holiness camp meetings, and in 1889 he began publishing in Philadelphia the periodical Christian's Pathway to Power, to which Hannah Smith contributed frequently. She began preaching as well.

In 1874 Smith traveled to England to join her husband, who had gone there the year before, and the two became the most prominent figures in the interdenominational Higher Life movement that swept up masses of followers in 1873–75. Hannah Smith was known as the “angel of the churches” both for her eloquence and for her appearance in her evangelistic addresses to huge gatherings throughout Britain. The Smiths' work in Britain came to a sudden end in 1875 when Robert was implicated in a scandal, and they returned to Philadelphia.

Hannah Smith then turned to writing. In 1875 she published The Christian's Secret of a Happy Life, a guide to sanctification and complete surrender to divine will that was translated into several languages and sold some two million copies around the world. She wrote several more books, including Every-day Religion; or, The Common-sense Teaching of the Bible (1893) and The Unselfishness of God and How I Discovered It: A Spiritual Autobiography (1903), as well as numerous pamphlets, tracts, and articles. She became a prominent advocate of college education for women and in that regard was a strong influence on her niece, Martha Carey Thomas (Thomas, Martha Carey). She helped found the Woman's Christian Temperance Union in 1874 and in 1883 became superintendent of its new Evangelistic Department.

In 1888 Smith and her husband moved to London, where their home was frequented by intellectuals, artists, and reformers, including Bernard Berenson (Berenson, Bernard) (who married their daughter Mary), Bertrand Russell (Russell, Bertrand) (who married their daughter Alys), George Bernard Shaw (Shaw, George Bernard), Henry (James, Henry) and William James (James, William), Israel Zangwill (Zangwill, Israel), Sidney and Beatrice Webb (Webb, Sidney and Beatrice), and George Santayana (Santayana, George). Hannah Smith continued to work with the British Women's Temperance Association, to preach occasionally, and to write. Her son, Logan Pearsall Smith (1865–1946), became a noted essayist and critic.