Mary Theresa Ledóchowska, SSPC; 29 April 1863 – 6 July 1922), was a Polish religious sister in the Roman Catholic church.

Members of the Polish nobility, she and her siblings – including Wlodimir Ledóchowski, Superior General of the Society of Jesus, and St. Ursula Ledóchowska – were born in Loosdorf, the Lower Austrian estate that belonged to their parents, Count Antoni Halka-Ledóchowski and Countess Josephine Salis-Zizers.

She was educated by the Sisters of Loreto in Sankt Pölten and displayed a strong Catholic piety, as was typical in her family.

[3] From 1885 to 1890, in order to help her family, which had fallen into economic difficulties, she obtained the position of lady-in-waiting to Princess Alice of Parma, the Grand Duchess of Tuscany, at the imperial palace in Salzburg.

The page of letters evolved into a monthly magazine, which made its debut in 1889, with her as the publisher, rare for a woman in the 19th century.

[8] The magazine soon became a full-time job, and Ledóchowska left her duties at the imperial court in 1891 so as to devote all of her time and energy to the missions.

Struggling to find financial support for her project, she lived in near poverty, surviving on a prebend granted to her by Empress Elisabeth of Austria.

She began to recruit other women as "auxiliary missionaries", whom she organized in 1894 as the Sodality of St. Peter Claver for the African Missions and the Liberation of Slaves, an association of laywomen.

She placed her work – publicizing the needs of the missions in Africa and raising funds for them – under the patronage of the Spanish Jesuit missionary, Peter Claver, who spent a lifetime in service to the enslaved African people brought to South America, which earned him the title of "Apostle to the Slaves"; he had recently been declared a saint.

[3] On April 29, 1894, Pope Leo XIII formally blessed the enterprise, approving the Sodality of St. Peter Claver as a Pious association of the faithful.

[13] Pope Paul VI beatified her on October 19, 1975, together with Arnold Janssen, Josef Freinademetz, and Eugène de Mazenod.