Mary Arthur McElroy
 Mary Arthur McElroy (July 5 1841 – January 8 1917) was the sister of the 21st President of the United States Chester A. Arthur and served as a hostess for his administration (1881–1885). She assumed the role because Arthur's wife Ellen Lewis Herndon Arthur had died only a year and a half earlier.Mary Arthur was born in Greenwich New York to William and Malvina S. Arthur. She was the last of nine children.