Sister Ancilla Dent, OSB (born 3 June 1933) is an English Roman Catholic nun, ecological activist, and writer.
Born as Rosamond Mary Dent, she took the religious name of Sister Ancilla upon becoming a Benedictine nun. She was a nun at St Mildred's Abbey, Kent, England. The elder daughter of William Dent and his wife, Mary, the 19th Baroness Furnivall (27 May 1900 – 24 December 1968), she and her younger sister, Patricia Bence (born 4 April 1935), are the descendents of Barons Furnivall. The barony has been in abeyance since 1968.