Her most famous novel is Egalias døtre ("The Daughters of Egalia"), which was published in 1977 in Norway. In the novel the female is defined as the normal and the male as the abnormal, subjugated sex. All words that are normally in masculine form are given in a feminine form, and vice versa.
Brantenberg was born in Oslo, but grew up in Fredrikstad. She studied English, History, and Sociology in London, Edinburgh, and Oslo. She has an English hovedfag (main subject, comparable to a Master), from the University of Oslo, where she also studied history and political science. She worked as a lector in Norwegian and Danish high schools, and she also held positions at the trade union for lectors (Norsk Lektorlag) and the Norwegian Authors' Union. Since 1982 she has been a writer full-time.
She worked from 1972-1983 in the Women's House in Oslo. She was a board member of the Norway's first association for homosexual people Forbundet av 1948, the precursor to the Norwegian National Association for Lesbian and Gay Liberation. She has established women's shelters and has worked in Lesbisk bevegelse (Lesbian movement) in both Oslo and Copenhagen. In 1978 she founded a literary Women's Forum with the purpose of encouraging women to write and publish. She has published 10 novels, 2 plays, 2 translations, and many political songs, and has contributed to numerous anthologies.
Novels that have been published in English:
- What Comes Naturally (London, 1986)
- Egalia's Daughters, (Seattle 1986) or The Daughters of Egalia (London 1985)
- The Four Winds (Seattle, 1996).
- Stein Larsen, Jesper (8 July 2014). "Frontkæmper og forfatter" (in Danish). Jyllands-Posten. Retrieved 24 May 2017.