Maude Dominica Mary Petre (4 August 1863 – 16 December 1942) was an English Roman Catholic nun, writer and critic involved in the Modernist controversy.
Petre (pronounced Peter) was born at the family estate of Coptfold Hall, near the village of Margaretting, Essex, to an old recusant family on her father's side; her mother was a convert. Her grandfathers were the thirteenth Baron Petre and the fourth Earl of Wicklow. Petre was educated privately. In her early twenties she experienced some religious doubts and as a remedy she was advised by her Jesuit confessor Fr. Peter Gallwey to go to Rome and study St Thomas Aquinas. Reflecting many years later on her decision to follow this advice, Petre concluded that "it was a fairly crazy idea". Nevertheless, in 1885, at the age of 22, she left for Rome where for a year, under the direction of accredited professors, she immersed herself in the thought of Aquinas and in the neo-scholastic manuals then in use. Her aunt Lady Lindsay informed friends that "Maude has gone to Rome to study for the priesthood".
In 1890 Petre joined the Daughters of the Heart of Mary, a community founded in France during the Revolution and consequently more liberal than many of the more traditional female religious institutes. In particular, it allowed members to live in their own homes and wear street clothing instead of habits. She was named local superior in 1896 and provincial in 1900.
In 1900 she began a friendship with the Jesuit priest George Tyrrell and they soon became part of a circle of questioning Catholic intellectuals. Petre already knew Friedrich von Hügel from her childhood, when he was one of her mother's most favoured visitors. He introduced both her and Tyrrell to the work of Alfred Loisy. She had got to know Henri Bremond while visiting the headquarters of her religious community in Paris. Through her, Bremond and Tyrrell became acquainted. When Tyrrell was expelled from the Jesuits in 1906, Petre, who had bought Mulberry House in Storrington, Sussex, had a cottage built for him in the garden and settled an annuity on him.