Mary Frances Dawson, Countess of Dartrey, 24th Baroness de Ros of Helmsley, was a British peer. She was born in London. Her parents were the Dudley FitzGerald-de Ros, 23rd Baron de Ros and Lady Elizabeth Egerton. Upon her father's death in 1907, Mary succeeded to the title.
- Occupation
- politician
- Citizenship
- United Kingdom, United Kingdom of Great Britain and Ireland
- Born
- July 31, 1854
- Died
- May 4, 1939
