Mary Leader (b. Wisconsin, 19 March 1918; d. Mequon, Wisconsin, 27 April 2004)
Mary E. Bartelt was apparently the only child of Arthur H. Bartelt (1878-1952) and his wife Mabel Hall Duncan (1882-1964). (The surname "Bartelt" is sometimes given incorrectly as "Bartlet.")
Little is known of her early life. She married Eric S. Leader (1910-1973), sometime after 1940; they had no children. At the time of her death, she had lived in Mequon, Wisconsin, for many years. As Mary Leader she published two novels, both supernatural in nature, Triad (New York: Coward, McCann & Geoghegan, [February] 1972), and Salem's Children (New York: Coward, McCann & Geohegan, [May] 1979). The author blurb on Triad notes that Leader had had "a varied career as both actress and journalist."
Triad is the story of the haunting of a woman named Bronwen, apparently by her dead cousin named Rhiannon. As commercial fiction it was successful enough to have a book club edition, and a mass market paperback release and a British paperback edition. The book has some name recognition because the American singer and songwriter Stevie Nicks (b. 1948) read the Bantam paperback, and was intrigued by the name "Rhiannon" so much that she wrote a song of that name for Fleetwood Mac, which became very popular. Nicks expressed little interest in the novel per se, saying "I just thought the name was so pretty that I wanted to write something about a girl named Rhiannon."
Salem's Children was much less successful. Kirkus called it "a reincarnation novel of agonizing boredom," noting that "Leader has clearly done some homework about the culture of witchcraft in old Salem, but her mixture of research and romantic suspense is hysterically pitched and not believable for a millisecond" (Kirkus, 28 March 1979).
An early manuscript version of Triad is held in the Wisconsin Historical Society Archives, along with an analysis of the Constitution by Leader's father, Arthur Bartelt.