NESTOS was a River-God of Bistonia in Thrake (modern day northern Greece).
The River Nestos flowed into the Aegean Sea near the town of Abdera opposite the island of Thasos. The major neighbouring rivers were the Hebros in the east, and Strymon to the west.
NESSUS (Nessos). The god of the river Nestus (also called Nessus or Nesus) in Thrace, is described as a son of Oceanus and Tethys. (Hes. Theog. 341.)
Source: Dictionary of Greek and Roman Biography and Mythology.
Hesiod, Theogony 337 ff (trans. Evelyn-White) (Greek epic C8th or 7th B.C.) :
"Tethys bore to Okeanos the swirling Potamoi (Rivers) . . . silver-swirling Akheloios, Nessos and Rhodios [in a list of rivers]."
- Hesiod, Theogony - Greek Epic C8th-7th B.C.