Mary Eddy Kidder (January 31, 1834 – June 25, 1910) was an American missionary and educator in Japan.

She was born into a devoutly Christian family in Wardsboro, Vermont, United States, and was educated there.

She taught at the Wardsboro Academy run by the Dutch Reformed Church of America.

In 1881, she retired as administrator of the school and moved to Tokyo, where she continued to do missionary work.

In 1873, she married Edward Rothesay Miller, a Presbyterian missionary who afterwards converted to the Reformed Church.