Strymon is the river-god of the Thracian Strymon (Struma), son of Oceanus and Tethys in Hesiod's catalogue. He is father of the Trojan-war king Rhesus by a Muse (Euterpe, Calliope, or Terpsichore in competing lists), and of other Thracian eponyms; Apollodorus also has Heracles choke the once-navigable stream with rocks when driving Diomedes' cattle home. The river marks Edonian country in the Lycurgus–Dionysus tale.
Adapted from Wikipedia, "Strymon (mythology)" · CC BY-SA 4.0
I.Genealogy and children
Hesiod numbers Strymon among the eddying rivers Tethys bore to Oceanus. As a Thracian king-god he fathers Rhesus by a Muse — Apollodorus names Euterpe, admitting Calliope as an alternate; other lists give Terpsichore. Homer's Doloneia knows Rhesus only as son of Eïoneus and never names the Muse or the stream.
Other children in the mythographic tradition include Olynthus and Brangas; by Neaera a daughter Evadne (wife of King Argus); Tereine (mother of Thrassa by Ares); and Rhodope (mother of Athos by Poseidon).
II.Thrace: Dionysus and Heracles
The Edonians dwelt beside Strymon when Lycurgus son of Dryas insulted Dionysus; the god fled to the sea with Thetis while the Bacchanals were seized — the river as northern edge of that conflict.
In Heracles' eighth labour, after the hero collected the man-eating mares' cattle of Diomedes with difficulty, Apollodorus says he blamed the river Strymon and, whereas it had been navigable, filled it with rocks and made it unnavigable. Hellenistic and later coinage of the region sometimes shows the river-god's head.