Sinon

Cyclopedia of Biblical, Theological and Ecclesiastical Literature

in Grecian mythology, was a son of Aesimus or Sisyphus, grandson to Autolycus, and related to Odysseus, and was said to have permitted the Trojans to make him prisoner in order to persuade them to admit the wooden horse within their walls. He represented that it had been constructed in atonement for the robbery of the Palladium, and succeeded in obtaining its admission into Troy, after which he gave the preconcerted signal and opened the door in the horse through which the Greeks poured forth and took possession of the city.

The Nuttall Encyclopedia

A wily Greek who beguiled the Trojans and persuaded them to admit the Wooden Horse into the city, to its ruin.