William Morton Fullerton (18 September 1865 – 26 August 1952) was an American print journalist, author and foreign correspondent for The Times.

In 1890, four years after his graduation from Harvard, Fullerton moved to France to begin work for The Times office in Paris.

Morton has been described as "Singularly attaching… a dashing well-tailored man with large Victorian moustache and languid eyes, a bright flower in his button hole, and the style of a 'masher'.

After the affair ended, Wharton, who was fiercely guarded when it came to her private life, requested that Fullerton destroy every letter she had ever sent him in order to avoid any scandal.

The affair probably helped inspire an erotic fragment for Beatrice Palmato, a novel that Wharton outlined but did not pursue, given that the incestuous father-daughter relationship at its core would make it unpublishable.