American religious leader, founder, with her husband, of the Unity School of Christianity, a movement that propounded a pragmatic healing and problem-solving faith.

Mary Caroline Page, who later took the name Myrtle, grew up in a strict Methodist home. After a year at Oberlin College (1868–69), she became a schoolteacher. In 1881 she married Charles Fillmore.

Myrtle Fillmore, who suffered from incipient tuberculosis, could find no relief in orthodox medical treatment. In 1886 she turned to mental healing as described in a series of lectures by E.B. Weeks, a student of the ex-Christian Scientist (Christian Science) Emma Curtis Hopkins. Fillmore found her health greatly improving; her husband, skeptical at first, soon joined in her enthusiasm as he found his leg, which had been stunted and weak since a childhood accident, growing stronger. They resolved to devote themselves to evangelizing for “practical Christianity,” an active faith able to effect solutions to physical, mental, financial, and other problems.

In 1889 they began publication of a magazine called Modern Thought (after 1895 called Unity). In 1893 they began publishing a second magazine, Wee Wisdom, for children. In 1890 they organized the Society of Silent Unity, which offered the service of effective prayer on behalf of beset persons who wrote to request it. Though it was not their intention, the organizational structure came to closely resemble that of a denomination, with a training school turning out ministers and with hundreds of separate Unity “churches” throughout the Midwest and in California. A basic text, Lessons in Truth, was published in 1908 by one of their most influential converts, Harriette Emilie Cady of New York City, a former homeopathist.

The Unity School of Christianity grew rapidly, and after World War I the Fillmores built a permanent home for the Unity movement at Lee's Summit. After Myrtle Fillmore's death the Unity movement continued to prosper under her husband, who was succeeded in turn by their sons.