Gautr, Gauti, Guti, Gothus and Geat are name forms based on the same Proto-Germanic root, *ǥuđ- (see God). Gapt is generally considered to be a corruption of Gaut.
The names may represent the eponymous founder of an early tribe ancestral to the Gautar (Geats), Gutans (Goths) and Gutes (Gotlanders). Gaut was one of Odin's names and the name forms are thought to be echoes of an ancient ancestry tradition among Germanic tribes, such as that of Yngvi, Freyr and the Ingaevones.
Moreover, the names Geats, Goths and Gutes are closely related tribal names. Geat was originally Proto-Germanic *Gautoz, and Goths and Gutes were *Gutaniz. According to Andersson (1996), *Gautoz and *Gutaniz are two ablaut grades of a Proto-Germanic word with the meaning "to pour" (modern Swedish gjuta, modern Danish gyde, modern German giessen; English in-got,gushing) designating the tribes as "pourers of metal" or "forgers of men".
The name Gautr appears as one of the names of Odin in Norse mythology, but also as an alternative form of the name Gauti, who was one of Odin's sons, and the founder of the kingdom of the Geats, Götaland (Gautland/Geatland), in Bósa saga ok Herrauðs (c. 1300). This Gautr/Gauti also appears as the father of the recurrent and undatable Geatish king Gautrekr in that saga, and several other sagas produced between 1225 and 1310.
Some versions of the English royal line of Wessex add names above that of Woden, purportedly giving Woden's ancestry, though the names are now usually thought be in fact another royal lineage that has been at some stage erroneously pasted onto the top of the standard genealogy. Some of these genealogies end in Geat, whom it is reasonable to think might be Gaut, while others continue with Geat's father Tatwa and even further. In the Life of Alfred (893), Asser states that the pagans worshipped this Geat himself for a long time as a god, quoting a disdainful verse attributed to Coelius Sedulius (5th century). The 10th century poem of Deor briefly mentions Geat, and his wife Maethehilde. The account in the Historia Britonum (c. 835; generally attributed to Nennius) says Geat was considered the son of a god by the heathens of England, but elsewhere it names Gothus, a son of Armenon, as the Goths' ancestor.
Jordanes in The origin and deeds of the Goths (551) traces the line of the Amelungs up to Hulmul son of Gapt, purportedly the first Gothic hero of record. This Gapt is felt by many commentators to be an error for Gaut or Gauti.
The Gutasaga (c. 1300), which treats the history of Gotland before its Christianization, begins with Þjelvar and his son Hafþi, who had three sons, Graipr, Guti and Gunfjaun, who were the ancestors of the Gotlanders, the Gutes (which is originally the same name as Goths).
The German chronicler Johannes Aventinus (ca. 1525) reported Gothus as one of 20 dukes who accompanied Tuisto into Europe, settling Gothaland as his personal fief, during the reign of Nimrod at Babel. The Swede Johannes Magnus around the same time as Aventinus, wrote that Gothus or Gethar, also known as Gogus or Gog, was one of Magog's sons, who became first king of the Goths (Geats) in Gothaland. Magnus separately listed Gaptus as son and successor of Beric, first king of the Goths south of the Baltic.