Saint Magnus Erlendsson, Earl of Orkney, sometimes known as Magnus the Martyr, was Earl of Orkney from 1106 to about 1117.

Magnus's grandparents, Thorfinn the Mighty, Jarl of Orkney 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 was related to the Norwegian Kings Olav II and Harald II.