the son of Rhotestus, was king, or according to Ammianus Marcellinus (27.5), "judex" of the West Goths during their stay in Dacia. His name became first known in A. D. 367, when the Goths were attacked by the emperor Valens, who first encamped near Daphne, a fort on the Danube, from whence, after having laid a bridge of boats over this river, he entered Dacia. The Goths retired and the emperor retreated likewise after having performed but little. He intended a new campaign, but the swollen waters of the Danube inundated the surrounding country, and Valens took up his winter quarters at Marcianopolis in Moesia. In 369, however, he crossed the Danube a second time, at Noviodunum in Moesia Inferior, and defeated Athanaric who wished for peace, and who was invited by Valens to come to his camp. Athanaric excused himself, pretending that he had made a vow never to set his foot on the Roman territory, but he promised to the Roman ambassadors, Victor and Arinthaeus, that he would meet with the emperor in a boat on the Danube. Valens having agreed to this, peace was concluded on that river, on conditions not very heavy for the Goths, for they lost nothing; but their commerce with Moesia and Thrace was restricted to two towns on the Danube. Thence probably the title " Gothicus," which Eutropius gives to Valens in the dedication of his history.

In 373, Athanaric, who belonged to the orthodox party, was involved in a feud with Fritigern, another "judge" of the West-Goths or Thervingi, who was an Arian, and oppressed the Catholic party. In 374, the Gothic empire was invaded by the Huns. Athanaric defended the passages of the Dnieper, but the Huns crossed this river in spite of his vigilance and defeated the Goths, whereupon Athanaric retired between the Pruth and the Danube, to a strong position which he fortified by lines. His situation, however, was so dangerous, that the Goths sent ambassadors, among whom probably was Ulphilas, to the emperor Valens, for the purpose of obtaining dwelling places within the Roman empire. Valens received the ambassadors at Antioch, and promised to receive the West-Goths as " foederati." Thus the West-Goths (Thervingi) settled in Moesia, but Athanaric, faithful to his vow, refused to accompany them and retired to a stronghold in the mountains of Dacia. There he defended himself against the Iluns, as well as some Gothic chiefs, who tried to dislodge him, till in 380 he was compelled to fly. Necessity urged hint to forget his oath, he entered the Roman territory and retired to Constantinople, where the emperor Theodosius treated him with great kindness and all the respect due to his rank. He died in 381. (Amm. Marc. 27.5, 30.3; Themistius, Orat. in Valent.; Zosimus, 4.34, 35; Sozomen. 6.37; Idatius, in Fastis, Syagrio et Eucherio Coss.; Eunapius, Fraym. pp. 1819, ed. Paris.)