Hippocoön (Ancient Greek: Ἱπποκόων) in this atlas entry is the Thracian counsellor and kinsman of Rhesus who, awakened by Apollo (or Athena's baleful dream in Homer), is first to discover the slaughter Odysseus and Diomedes wrought in the Thracian camp during the night raid.
Adapted from Wikipedia, "Hippocoon" · CC BY-SA 4.0
I.Kinsman of Rhesus
In Iliad 10, after Diomedes kills Rhesus and twelve comrades and Odysseus drives off the snow-white horses, a divinity rouses Hippocoön. He finds the horse-stall empty and the men gasping in blood, groans, and raises the alarm among the Trojans.
He is a night-raid witness, not a battlefield captain with an independent aristeia.
II.Homonym care
Distinct from the Spartan Hippocoon who seized Tyndareus' throne, from genealogical Hippocoons in Amphiaraus' stemma, and from Virgil's archery-contest son of Hyrtacus. The atlas id hippocoon-thrace is the Thracian kinsman of Rhesus alone.