Cadmus and Harmonia
According to the Bibliotheca, Illyrius was the youngest son of Cadmus and Harmonia who eventually ruled Illyria and became the eponymous ancestor of the whole Illyrian people. Illyrius was specifically born during an expedition against the Illyrians on the side of the Encheleans.
Polyphemus and Galatea
According to the Illyrian Wars of Appian, Illyrius was the son of the Cyclops Polyphemus and his wife Galatea with siblings Celtus and Galas. The children of Polyphemus all migrated from Sicily and ruled over the peoples named after them, the Celts, the Illyrians, and the Galatians. This particular genealogy was most likely composed by the ancient Greek founders of Epidamnus (Corinthians and Corcyrans) and preserved in Appian's work.
Illyrius had six sons and three daughters whose names were associated with specific tribes:
- Encheleus (Εγχελέα) of the Enchelaeae
- Autarieus (Αυταριέα) of the Autariates
- Dardanus (Δάρδανον) of the Dardani
- Maedus (Μαίδον)
- Taulas (Ταυλαντά) of the Taulantii
- Perrhaebus (Περραιβόν) of the Perrhaebi
- Pannonius or Paeon (son of Autarieus) of the Pannonians
- Apollodorus; Hard, Robin (1999). The Library of Greek Mythology. Oxford University Press. ISBN 0-19-283924-1.
- Grimal, Pierre; Maxwell-Hyslop, A. R. (1996). The Dictionary of Classical Mythology. Wiley-Blackwell. ISBN 0-631-20102-5.
- Lewis, D. M.; Boardman, John; Hornblower, Simon; Ostwald, M. (1994). The Cambridge Ancient History, Volume 6: The Fourth Century BC. Cambridge University Press.
- Wilkes, John J. (1995). The Illyrians. Oxford: Blackwell Publishing. ISBN 0-631-19807-5.