Hrafnhildur's parents are Ragnar Á. Magnússon, chartered accountant (1917–1988) and Svanlaug I. Gunnlaugsdóttir, housewife (1920–1978). Hrafnhildur is married to Pétur Gunnarsson, writer. They have two sons: Dagur Kári, film director, and Gunnar Þorri, literary scholar and translator.