Halldóra was born on the farm of Helguhvammur in north Iceland. A week after her birth her mother died, and she was taken in by the farmer and
his wife, who brought her up. Halldóra studied at the Women’s College in Blönduós in 1947–1948. Shortly after that she met Ólafur Þórhallsson, who farmed with his parents in Vatnsnes and wrote on historical subjects. In 1983 the couple moved to Reykjavík due to illness in the family. They lost two sons in succession, which was a traumatic experience that marked them for life.
Halldóra loved music, and for as long as her health permitted she sang in a church choir. She was good with her hands, and when bath- ing her grandchildren she came up with the idea of making paper boats for them to play with. Níels Hafstein, who was then chair of the Living Art Museum, heard about her boats, and commissioned her to make some for the exhibition From the Heart in 1991. The paper boats are a reflection of life on the Vatnsnes peninsula: transporting wool to market, catching fish for the pot, carrying driftwood from Strandir, and buying supplies for the home. Works by Halldóra were later showcased at the Icelandic Folk and Outsider Art Museum, and were in the Museum’s exhibition Across the Bridge of Optimism at the Reykjavík Art Museum in 2003.