Magnús Eiríksson was also the Old Norse name of Magnus IV of Sweden.Magnús Eiríksson (22 June 1806 in Skinnalón (Norður-Þingeyjarsýsla), Iceland – 3 July 1881 in Copenhagen, Denmark) was an Icelandic theologian and a contemporary critic of Søren Aabye Kierkegaard (1813–1855) and Hans Lassen Martensen (1808–1884) in Copenhagen.
Due to his very critical attitude towards the church dogma, especially the dogmas of the Trinity of God and the Divinity of Christ, in contrast to which he stressed (at least in his late work) the essential unity of God and the leadership of Jesus (merely) as prophet and teacher, Eiríksson often was labeled as a “pioneer” or “precursor” to the Unitarian movement in Denmark.