William Mackintire Salter (January 30, 1853 – July 18, 1931) was the author of several books on philosophy and a critical and enduring major classic on Nietzsche.

He was also a special lecturer for the Department of Philosophy in the University of Chicago[1] and a pioneer in the Ethical movement.

Mary's sister, Alice Howe Gibbens, was the wife of philosopher and psychologist William James.

[5] On 2 December 1889[5] she died of the measles, and they later adopted Frank Gray, renaming him John Randall Salter.

[6] Salter's book, Ethical Religion, influenced Mohandas K. Gandhi, who published a summary in Gujarati in 1907.