Question: What was the name of Gudrød Bjørnsson's grandfather, who is also known as the first King of Norway?

Context articles: Harald Fairhair
Gudrød Bjørnsson
House of Theemuge
Eric of Pomerania
Bjørn Farmann
Rothesteus
Ragnvald Sigurdsson
Colmán mac Cobthaig
Gudrød the Hunter
Christian VI of Denmark

Harald Fairhair (Old Norse: "Haraldr Hárfagri", Norwegian: "Harald Hårfagre", (literally "Harald Fair-hair") ;  850 –  932) is remembered by medieval historians as the first King of Norway.
 According to traditions current in Norway and Iceland in the twelfth and thirteenth centuries, he reigned from  872 to 930.
 Most of his life remains uncertain, since the extant accounts of his life in the sagas were set down in writing around three centuries after his lifetime.
 A few remnants of skaldic praise poems attributed to contemporary court poets exist which seem to refer to Harald's victories against opponents in Norway.
 The information supplied in these poems is inconsistent with the tales in the sagas in which they are transmitted, and the sagas themselves often disagree on the details of his background and biography.
 Two of his sons, Eric Bloodaxe and Haakon the Good, succeeded Harald to become kings after his death.
Gudrød Bjørnsson was the son of Bjørn Farmann, the king of Vestfold, and a grandson of Harald Fairhair.
 Gudrød was the father of Harald Grenske, and the paternal grandfather of Saint Olaf.
Theemuge Dharikolhu (Dhivehi: ތީމުގޭ ދަރިކޮޅު) or Homa Dharikolhu (Dhivehi: ހޯމަ ދަރިކޮޅު) was one of the early dynasties of the Maldives that reigned from c.1117 (or earlier) until c.1388.
 According to the record in the Isdhoo Loamaafaanu (copper plates), which was written in 1194, the first king of the Theemuge Dynasty extended his rule to cover the entire Maldives.
 The writing suggests that the king united the entire country under his rule, bringing to an end a number of fiefdoms throughout the country.
 The first king of the Theemuge Dynasty is known as Siri Mahabarana and he is believed to be Koimala Kalo.
 Sri Mahabarana was proclaimed king in the year 1117 or 1118.
 Other sources suggest that the Theemuge Dharikolhu was the new name of the Soma Vansa Lunar Dynastry after the conversion to Islam of King Dhovemi which lasted from c.1153 to c.1388.
 In this case King Dhovemi, the fifth king of the Lunar Dynastry became the first King of the Theemuge Dynastry.
Eric of Pomerania KG (1381 or 1382 – 24 September 1459) was King Eric (Eirik) III of Norway (1389–1442), King Eric VII of Denmark (1396–1439), and King Eric ("Ericus") of Sweden (1396–1439), in all three known mainly as "Erik af/av Pommern".
 He was the first King of the Nordic Kalmar Union, succeeding his adoptive mother Margaret I of Denmark, and was also Duke Eric I of Pomerania.
Bjørn Farmann ("Bjørn the Tradesman", also called Bjørn Haraldsson, Farmand and Kaupman, c. ?
 – c. 930–934) was a king of Vestfold.
 Bjørn was one of the sons of Harald Fairhair, the first king of Norway.
 Bjørn Farmann was also the great-grandfather of Olaf II of Norway, through his son Gudrød Bjørnsson.
Rothesteus (flourished in 4th century), also known as Rothesteos, Rothestes, also Radistis was a Gothic sub-king under the Thervingian chieftain Athanaric.
 According to Christian Settipani, he was the father (or paternal grandfather) of Alaric I, the first king of the Visigoths, and the father of Atharid, who played a leading role in the killing of the Christian martyr Sabbas the Goth.
Ragnvald Sigurdsson (750 – after 814) was a Lord on Huseby in Lista while Harald Granraude was king of Agder.
 He had two children: Gunhild Ragvaldsdatter and Olve Ragnvaldsson.
 He is most known for marrying his daughter Gunnhild to Harald Granraude, who was killed by Gudrød the Hunter.
 What happened to Ragvald after is not known.
 He is also known to be the great-great-grandfather of Harald Hårfagre.
Colmán mac Cobthaig (died 622) was a king of Connacht from the Ui Fiachrach branch of the Connachta.
 He was the first king of Connacht from the Ui Fiachrach Aidhne branch.
 This branch was descended from Eochu, the brother of Ailill Molt (died 484).
 According to the "Book of Ballymote" he was the grandson of Goibnenn mac Conaill (flor.537), the first Aidne king mentioned in the annals, but "Rawlinson Genealogies" name his grandfather as Gabrán.
Gudrød the Hunter (Old Norse: "Guðrǫðr veiðikonungr", Norwegian: "Gudrød Veidekonge", litterary "Gudrod Hunterking"), also known as the Magnificent (Old Norse: "enn gǫfugláti", Norwegian: "den gjeve"), is a legendary character portrayed in the Norse sagas as a Norwegian petty king in the early 9th century.
 According to the sagas, he was the father of Halfdan the Black, and thus the grandfather of Harald Fairhair, the first king of unified Norway.
 He is considered by modern historians to be of a more mythical nature than other ancestors of Harald and Halfdan, and he can not be identified historically.
 Historians have in turn made a number of proposals seeking to identify him with various would-be contemporary historical figures.
Christian VI (30 November 1699 – 6 August 1746) was King of Denmark and Norway from 1730-46.
 The eldest surviving son of King Frederick IV and Louise of Mecklenburg-Güstrow, he is considered one of Denmark's more anonymous kings, but he was a skilled politician, best known for his authoritarian regime.
 He was the first king of the Oldenburg dynasty to refrain from entering in any war.
 He was married to Sophia Magdalene of Brandenburg-Kulmbach and was the father of Frederick V.
 His chosen motto was "deo et populo" (for God and the people).