Gretta may refer to:
- Gretta Boley, United States forester.
- Gretta Bowen (1880-1981), self-taught Irish artist.
- Gretta Chambers (born 1927), Canadian journalist and former Chancellor of McGill University.
- Gretta Cohn, United States cellist and radio producer.
- Gretta Duisenberg (born 1942), Dutch political activist.
- Gretta Kehoe-Quigley, former camogie player, captain of the All Ireland Camogie Championship
- Gretta Kok (born 1944), retired Dutch breaststroke swimmer.
- Gretta Lange Bader (1931 – 2014), United States sculptor.
- Gretta Sarfaty Marchant, international artist and curator.
- Gretta Taslakian (born 1985), Lebanese sprinter of Armenian descent.
- Gretta Taylor (née Francis), musician and teacher from Trinidad and Tobago.
- Gretta Vosper, Canadian minister, writer and leader within the Progressive Christianity movement.