Hermeric (died 441) was the king of the Suevi in Galicia from perhaps as early as 406 and certainly no later than 419 until his retirement in 438. He was a pagan and an enemy of the Roman Empire throughout his life. He is given a reign of thirty-two years in most manuscripts of Isidore of Seville's Historia Suevorum, but one manuscript does list his reign as fourteen years.
Hermeric led the Suevi across the frozen Rhine along with the Vandals and Alans in December 406. They crossed Gaul and the Pyrenees and settled in Hispania. While Theodore Mommsen believed the Suevi were foederati and Ernst Stein seconded the notion by believing they had made an agreement with the Roman usurper Magnus Maximus whereby they received the western half of Iberia, there is no primary evidence for any alliance between the Suevi and Rome. In 411 (according to Ludwig Schmidt) or 417 (according to Felix Dahn), Hermeric made a treaty with the Roman emperor Honorius, but in fact the only event of note in 411 was the division of Iberia sorte (by lot) between the barbarian peoples. The east of the province of Gallaecia with its capital of Braga (Bracara Augusta) fell to the Suevi, while the west of the province went to the populous Hasdingi.
Between 416 and 418, the Visigoths under Wallia made war on Hermeric on behalf of Rome. In 419, after a personal dispute between Hermeric and the Vandal king Gunderic, the Vandals attacked the Suevi and trapped Hermeric in the Nervasian (Erbasian) Mountains before the Roman general Asterius intervened and the Vandals retreated. Thereafter, until the Vandals left Iberia for Africa in 429, Hermeric remained peaceful, but in 430 he began to raid Gallaecia.
In 431 a Gallaecian named Hydatius went to Flavius Aëtius to plead for help against the Suevi, but Aëtius delayed until 432 the sending of the comes Censorius. According to Hydatius' Chronicle of contemporary events, the Gallaecian plebs in the better-fortified strongpoints defeated Hermeric and his men, inflicting heavy casualties and taking many prisoners, which forced the Sueves to release the Gallaecian families they had taken captive (430).
In 435, "on episcopal intervention", possibly Hydatius', Hermeric made peace with the Gallaecians. In that same year, Hermeric negotiated through the Catholic bishop Symphosius directly with the Western Roman Emperor. In 437, Censorius made a second expedition accompanied by Fretimund.
After seven years of illness, Hermeric was forced to retire from the kingship in 438 and pass it on to his son Rechila. The story, recorded in Isidore, that Hermeric sent Rechila to Baetica to defeat Andevotus, Romanae militiae dux, is false, as there is no contemporary evidence that Hermeric retained any authority after his abdication. There appears to have been no principle of elective monarchy among the Suevi and the successes of their raids may have accounted for the contentment of their people. Hermeric's royal line lasted until 456.
In 429, there appeared briefly a Suevic military leader named Heremigarius operating in Lusitania who may have been a joint monarch with Hermeric, but there is no primary source to prove it.