Saint Magnus, Earl Magnus Erlendsson of Orkney, sometimes known as Magnus the Martyr, is the first Earl of Orkney to bear this name, and rules from 1108 to about 1115.

His story is told in two sagas, Magnus' saga the shorter and longer and one legend, Legenda de sancto Magno.

Magnus's grandparents Earl Thorfinn and his wife Ingibiorg Finnsdottir had two sons, Erlend and Paul, who were twins.

Through Ingibiorg's father Finn Arnesson and his wife, the family is related to the Norwegian Kings Olav II and Harald II.