Maren Margrethe Thomsen, known as Maren Margrethe "Grethe" Bartram and "Thora" (23[source?] February 1924 – c. 31 January 2017) was a Danish war criminal.
She was known for informing on at least 53 people from the Danish resistance movement during the Second World War. It resulted in the early communist resistance groups being dismantled and many of their members being sent to concentration camps. Bartram informed on her brother, husband and close friends.
Bartram was given the death penalty after the war but was later pardoned and the sentence was changed to life in prison. In 1956 she was released and moved to Halland in Sweden where she lived under her married name.
Bartram's was announced on 31 January 2017. She had died at her home in Halland, aged 92.
- "Gestapos Største Stikker" (in Danish). Samvirke. Retrieved 28 August 2015.
- Grethe Bartram – biography in Dansk Kvindebiografisk Leksikon
- Storstikkeren – Chapter 10 in Erik Haaests book, Udyr – eller hvad from 1977 in an updated e-version from 2006.
- Myter, Mordet i Højbjerg, Marie Lock-Hansen, Forlaget Din Bog