Lettice Mary Tredway (1595 – October 1677), courtesy title Lady Tredway, was an English abbess.
In July, 1616, Lady Tredway entered the novitiate of the Canonesses Regular of the Lateran of Notre-Dame-de-Beaulieu at Sin, near Douai (where she was probably educated), and in October 1617, made her solemn profession.
In 1631 she and Miles Pinkney, better known as Father Carre, a priest of the English College at Douai, conceived the project of opening a house for canonesses for English subjects only at Douai. The idea was approved by the Catholic authorities at home and abroad, and in 1634 it was decided to open this English convent at Paris.
Father Richard Smith, Bishop of Chalcedon, then in exile in Paris, helped them generously and may be counted a co-founder. He blessed Lady Tredway as abbess, and the Convent of Notre-Dame-de-Sion was permanently established in the Rue des Fosses in 1639. Father Carre and Lady Tredway were also practically the founders of the Seminary of St. Gregory for training priests for the English mission. A pension for English ladies and a school were attached to the new convent, of which Lady Tredway held the office of abbess till 1675, when illness compelled her to resign.
After her death the superiors held the title of prioress.
She was the daughter of Sir Walter Tredway, of Buckley Park, Northamptonshire; her mother was Elizabeth Weyman.