Mary B. Hadden (1834-?) was born in Perth Amboy, New Jersey, and died in an unknown location. In 1885, Hadden wrote to Mary Baker Eddy asking for information about studying at the Massachusetts Metaphysical College. Despite this interest, there is no record of Hadden studying with Eddy. Hadden achieved notoriety in 1899 when she was declared "supreme ruler over all things" by Charles W. Dean, her husband, and a small group of followers. It's not clear what eventually happened to Hadden and her followers.

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