Feletheus is the son of Flaccitheus, king of the Rugii and founder of the Kingdom of the Rugii; his brother is Ferderuchus.
Feletheus is married to the Goth Gisa, who is probably the cousin of the Amal Ostrogothic king Theodoric the Great.
After the death of his father, probably in 475, Feletheus had succeeded his father as king of the Rugii.
Their territory at the time was based in Lower Austria.
In 476, Feletheus had supported Odoacer and his Scirian and Herulian in overthrow of the Roman Emperor Romulus Augustus.
Feletheus is a close confidant of Severinus of Noricum.
After the Eastern Roman Emperor Zeno attempts to create conflict between the Rugii and Odoacer, Feletheus executes his brother Ferderuchus, who supported Odoacer.
Odoacer subsequently invades the Kingdom of the Rugii in 487, dealing them a crushing defeat in their own territory and taking Feletheus and his wife into captivity, later executing them in Ravenna.
