Þórunn Elfa Magnúsdóttir was the daughter of a worker from Reykjavík and was sent at the age of six to relatives in northern Iceland. She had to discontinue her studies because of tuberculosis and later became active in women's rights and writers' organisations.
In her debut work Dætur Reykjavíkur I-III, 1933-1938, she experimented with slang and hybrid genres and subsequently moved onto psychological realism in her novel Að Sólbakka, 1937, in which the main character is a woman day labourer. Her novels Snorrabraut 7, 1947, and Sambýlisfólk, 1954, describe a young couple's struggle for existence in war-time Reykjavík with its corruption and the black market. Her novel Frostnótt í maí, 1958, about a six-year-old girl's traumatic separation from her mother, represents the pinnacle of her writing.