Athanaric or Atanaric (Athanaricus; died 381) was king of several branches of the Thervingian Goths (Thervingi) for at least two decades in the 4th century. Throughout his reign, Athanaric was faced with invasions by the Roman Empire, the Huns and a civil war with Christian rebels. He is considered the first king of the Visigoths, who later settled in Iberia, where they founded the Visigothic Kingdom.
Athanaric made his first appearance in recorded history in 369, when he engaged in battle with the Roman emperor Valens and ultimately negotiated a favorable peace for his people. During his reign, many Thervingi had converted to Arian Christianity, which Athanaric vehemently opposed, fearing that Christianity would destroy Gothic culture. According to the report of Sozomen, 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. Along with his generals Muderic and Lagarimanus, Athanaric was later defeated by the invading Huns. Temporarily fleeing to Caucaland in the Carpathians, Athanaric was received by Theodosius I in Constantinople in 381, where he signed a treaty of friendship with the Roman Empire.
Socrates Scholasticus, Sozomen, and Zosimus refer to conflicts between Fritigern and Athanaric. Ammianus Marcellinus and Philostorgius do not record such conflicts.
According to Socrates, Fritigern and Athanaric were rival leaders of the (Therving) Goths. As this rivalry grew into warfare, Athanaric gained the advantage, and Fritigern asked for Roman aid. The Emperor Valens and the Thracian field army intervened, Valens and Fritigern defeated Athanaric, and Fritigern converted to Christianity, following the same teachings as Valens followed. Sozomen follows Socrates' account.
According to Zosimus, Athanaric (Athomaricus) was the king of the Goths (Scythians).