Catherine Josephine Seton (28 June 1800 - 3 April 1891) was the daughter of Elizabeth Ann Seton, founder of the Sisters of Charity of St. Joseph. She was the first American to join the Irish Sisters of Mercy.
In 1800, Catherine was born on the Island of Manhattan, but she grew up in Emmitsburg, MD where Elizabeth Seton founded her order of the Sisters of Charity. Her two siblings Rebecca Marie (1802-1816) and Anna Maria (1795-1812) died young. She was second generation American, and until Elizabeth's conversion from Episcopalian unto Catholicism was taught Episcopal Christianity.
After her mother Elizabeth Seton died, Catherine was adopted by her "second mother" Julie Scott from 1821 until 1842. During this period, she had three tours of Europe.
When Catherine Seton returned to New York, she became restless and vocal in her request for a proper vocation. The opportunity could not be met until the Sisters of Mercy planned the first colonization of their order from Dublin onto Manhattan. Thus, Catherine became the first adopted American Sister of Mercy at the opening of their New York foundation on 14 May 1846.
Catherine was referred to at first as "Sister Mary Catherine", her primary vocation being visiting those in prison. She visited thousands who were locked away in New York City, learning to speak French, German, Italian, and Spanish to communicate with each person. In the latter portion of her service, she was respectfully referred to as "Mother Mary Catherine". She held her vocation for more than forty five years.
She was affectionately called "the Angel of the Tombs" briefly during the Civil War while she acted as a far-stationed nurse for injured Union forces.