Athanaric or Atanaric (Gothic: Aþanareiks presumably from aþni "year" and reiks "king"; Latin: Athanaricus; died 381) was king of several branches of the Thervingian Goths for at least two decades in the 4th century. Athanaric made his first appearance in recorded history in 369, when he engaged in battle with the Eastern Roman Emperor Valens and ultimately negotiated a favorable peace for his people. During his reign, many Thervings had converted to Arian Christianity, which Athanaric vehemently opposed, fearing that Christianity would destroy Gothic culture. According to the report of Sozomenos, more than 300 Christians were killed in Athanaric's persecution during the 370s.
Fritigern, Athanaric's rival, was an Arian and had the favor of Valens, who shared his religious beliefs. In the early 370s, Athanaric successively fought Fritigern in a civil war, only to later be defeated by the invading Huns. Temporarily fleeing to Caucaland in the Carpathians, Athanaric was warmly received by Theodosius in Constantinople in 381, where he signed a treaty of friendship with the Eastern Roman Empire.
Socrates Scholasticus, Sozomen, and Zosimus refer to conflicts between Fritigern and Athanaric.Ammianus Marcellinus and Philostorgius do not record such conflicts.