Gothic mythology refers to the mythology of the Goths, a Germanic people. Very little is known about Gothic religion, but it is likely that they at least followed the common Germanic triad of Odin, Tyr, and Thor.
Deities
*Teiws
The Goths did have a cult of a god of war, identified by the Romans with Mars, presumably cognate to the Proto-Germanic Tīwaz, perhaps called *Teiws in Gothic, on the basis on the corresponding letter names.
Among the Tervingi perhaps also known as the Terwing, the tribe's mythical, eponymous ancestor, possibly related too to the Týrfingr lost sword legend – 'the finger' of the god Týr which on touch caused sudden death to its enemies.
Gaut
Then, there was Gaut or Gapt, the ancestor of the Amali dynasty, and presumably eponymous of the entire people of the "Goths"; it is unclear whether this deity should be considered independent of those just mentioned, or if it is just another name by which either of them was also known.
Old Norse Gautr in later centuries was considered another name for Odin in Scandinavia. It may also be significant, that in the Eddaic tradition, Odin himself is said to have come to the north from the "Black sea region / Turkland", i.e. the lands some believe was formerly and later inhabited by some ancestors of the Goths. If Gapt was the original "ansic" ancestor, later identified with Odin/Wodanaz, the Gothic letter name *ansuz (aza) may testify to his importance; but this does not imply that Gaut can be assumed to have had the same attributes typical of Odin in the Viking Age.
The Aesyr were considered the folk which the north-Germanic god Odin led in his Wuoth ('raging') Ghostly Host charging through the nights and battlefields. These are identified as the Aes (or Asians) of Antiquity, where the Indo-Iranian Alans were considered as the first gens that came off Asia beyond the Western Scythians or Sarmatians in the steppes ethnic geography for the Greek and classical sources.
These may be echoes that hark back to an older influence from many centuries earlier, when it is visible in the archaeological records the introduction of steppes elements from the Yamna Culture among the earliest Germanic cultural horizon, giving birth to the Corded Ware Culture from the Copper Age.
*Fairguneis, Ingwaz, and *Donaws
Another important god may have been called *Fairguneis, identified by the Romans as Jupiter (and presumed by modern scholars to be Thor), but this relies on the accuracy of the Romans' interpretation of Gothic religion.
The Gothic letter name enguz may indicate the existence among the Goths of the god Ingwaz, an older name for the Norse god Freyr, but there is no other evidence for this.
Finally, the river Danube may have also been deified, as *Donaws.
Witches
A Gothic belief in witches is attested with the story of the haliurun(n)ae (c.f. Anglo-Saxon hellrúne) who were expelled from the tribe by king Filimer, after which they mated with evil spirits and gave birth to the Huns, who eventually destroyed the Gothic empire.